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About this book

The Magnesium Technology Symposium, the event on which this collection is based, is one of the largest yearly gatherings of magnesium specialists in the world. Papers represent all aspects of the field, ranging from primary production to applications to recycling. Moreover, papers explore everything from basic research findings to industrialization. Magnesium Technology 2019 covers a broad spectrum of current topics, including alloys and their properties; cast products and processing; wrought products and processing; forming, joining, and machining; corrosion and surface finishing; and structural applications. In addition, there is coverage of new and emerging applications.

Table of Contents

Frontmatter

Magnesium Technology 2019: Keynote Session

Frontmatter

Magnesium Alloy Sheet for Transportation Applications

Wrought magnesium alloyMagnesium Alloy sheet has a long history in the aerospace sector and more recently has become popular for personal electronic applicationsApplications , but has yet to make the transition to high-volume applicationsApplications in the transportation sector. While there are clear market opportunities for magnesium sheetMagnesium sheet in lightweightLightweight vehicles, the adoption of the material has been limited by the price, the limited number of suppliers and distribution channels and the silicothermic production process. Although the use of a multi-stand mill would reduce the conversion cost and thus the price of magnesium sheetMagnesium sheet , the current market volume cannot justify investment in such an expensive high capacity plant. This paper reviews these factors and describes the possibility of using twin roll casting and a novel single stand mill design as an alternate, cost-effective, method to produce low-cost magnesium alloyMagnesium Alloy sheet to promote its implementation in the transportation market.

Chris Romanowski

Magnesium for Automotive Lightweighting: Status and Challenges

Cast and wrought magnesiumMagnesium have long been identified as a key pathway to automotiveAutomotive lightweighting and improved energy efficiency. However, adoption in the automotiveAutomotive market remains low. This talk will look at the application of magnesiumMagnesium components into various vehicle subsystems from 2012 through today and identify the technical challengesChallenges that currently limit full adoption.

Sarah Kleinbaum

Magnesium Process and Alloy Development for Applications in the Automotive Industry

While cast magnesiumMagnesium components have been extensively used in the automotive industryAutomotive industry , only niche applicationsApplications are known to exist for magnesiumMagnesium sheets to this date. This is believed to originate from limitations in the material property spectrum covered by existing alloys. By utilising the twin-roll castingTwin-roll casting technique, novel Mg–Zn–Ca–Zr (ZXK) alloy sheets can be developed with improved formabilityFormability as a result of a textureTexture weakening effect. More importantly, it can be shown that these new alloy sheets can be processed at industrial scale. Based on the magnesiumMagnesium -specific design of a Volkswagen Passat decklid, the advantages of these new highly formable sheets in an automotiveAutomotive production environment can be evaluated.

David Klaumünzer, Jose Victoria Hernandez, Sangbong Yi, Dietmar Letzig, Sang-hyun Kim, Jae Joong Kim, Min Hong Seo, Kanghwan Ahn

Thermally Activated Slip in Rare Earth Containing Mg–Mn–Ce Alloy, ME10, Compared with Traditional Mg–Al–Zn Alloy, AZ31

The thermally activated deformation of textured Mg alloys is evaluated using repeated stress relaxation tests analyzed with the assistance of elasto-viscoplastic self-consistent (EVPSC) polycrystal modeling. The data, presented in a Haasen plot, suggests that the superposition of at least two mechanisms controls the thermally activated glide of dislocations in both a rare-earth containing alloy, ME10, and the conventional alloy, AZ31: forest dislocation interactions and a mechanism with a lower activation volume (solute–dislocation interaction and/or cross-slip).

Vikaas Bajikar, Jishnu J. Bhattacharyya, Nathan Peterson, Sean R. Agnew

Magnesium Technology 2019: Alloy Design and Casting

Frontmatter

Bimodal Casting Process of Eco-Mg Series Alloys by Vertical High-Speed Press Machine

Ultimate advancements in non-flammable magnesium alloysMagnesium alloys (the so-called Eco-Mg alloysMg alloys series, acronym of Environment Conscious MagnesiumMagnesium ) have been recently achieved. Preliminary laboratory tests have been already confirmed safe window parameters (i.e. exposure time and maximum melting temperature) for processing Eco-Mg AZ91D-1.5CaO alloy in full liquid state. Further project challenge has been now completed; Eco-Mg samples have been realized in special novel pre-industrial vertical 4-column press machine, designed and constructed for processing Eco-Mg series alloys in air by two routes, by high-pressure die casting and by semisolid state injection. An external rotating stirrer finely controlled in temperature, and rotating velocity completes the semisolid processSemisolid process route, allowing Eco-Mg alloyMg alloy remaining below flame-ignition temperature. MicrostructureMicrostructure investigation on samples produced in both high-pressure die casting and semisolid state patterns has been performed. To date, such a bimodal pilot line is thought to introduce affordable industrial way e for producing near-net-shapeShAPE Mg parts.

Fabrizio D’Errico

Investigation of the Evolution of the Microstructure in the Directionally Solidified Long-Period Stacking-Ordered (LPSO) Magnesium Alloy as a Function of the Temperature

The influence of the LPSO-phase orientation and the temperature on the deformation mechanisms of directionally solidified Mg–Zn–Y magnesium alloyMagnesium Alloy has been investigated by neutron diffraction and acoustic emissionAcoustic emission (AE) technique. The results indicate that the kinking mechanism and activation of non-basal slip are Non-basal slip significantly temperature and orientation dependent with respect to the loading axis.

Daria Drozdenko, Kristián Máthis, Stefanus Harjo, Wu Gong, Kazuya Aizawa, Michiaki Yamasaki

TEM Studies of In Situ Formation of MgO and Al4C3 During Thixomolding of AZ91 Magnesium Alloy Conducted in CO2

MgO and Al4C3 compounds were produced in situ by reaction of CO2 with AZ91 alloy at semi-solid temperature range. Using modified magnesiumMagnesium injection molding, reactive carbon dioxide was introduced to hot zone of cylinder to conduct controlled oxidation reaction with partially melted Mg alloyMg alloy . In result, nano-scale native MgO (30–50 nm) and small amount of Al4C3 carbide within eutectic mixture consisted of α(Mg) and β-Mg17Al12 were formed. Apart from eutectic obtained directly from liquid state, proeutectic magnesiumMagnesium solid solution α(Mg)p is crystallized. Homogeneously distributed α(Mg) globular grains (not melted during the process) with size 20–50 μm and volume 8–12% were also visible in the microstructureMicrostructure . Electron beam was aligned along [011] zone axis of MgO and [01-10] of αMg matrix. (11-1) planes of MgO were parallel to (0002) planes of the matrix. Orientation relationship was [011] MgO ║ [01-10] αMg and (11-1) MgO ║ (0002) αMg.

Ł. Rogal, L. Litynska-Dobrzynska, Bogusław Baran

FFF of Mg-Alloys for Biomedical Application

Additive manufacturingAdditive Manufacturing is a very promising approach to patient-specific implants. In combination with degradability, individual tissue regeneration could be obtained. Like metal injection moulding (MIM), fused filament fabrication (FFF) of metal powders belongs to binder-based sinteringSintering technologies. However, FFF of metal powders does not require an expensive mould, but it offers individual prototyping of sophisticated shaped parts at low costs. FFF of metals is novel and processing of Mg powders is just at the start of development. In the present work, special Mg-alloy-powder-polymer blends were developed to enable manufacturing of flexible filaments and failure-free green parts. Consolidation to final metal parts took place using SF6-free powder metallurgical (PM) sinteringSintering technique. Test specimens and implant demonstrator parts were successfully produced. The specimens showed mechanical propertiesMechanical properties of up to 177 MPa UTS, 123 MPa yield strength and 2.8% elongation at fracture. Thus, the mechanical propertiesMechanical properties are equivalent to those of as-cast material. Based on these results, FFF appears to be a very promising approach to Mg implant production.

M. Wolff, T. Mesterknecht, A. Bals, T. Ebel, R. Willumeit-Römer

Effects of Gd/Y Ratio on the Microstructures and Mechanical Properties of Cast Mg–Gd–Y–Zr Alloys

Three Mg–xGd–yY–0.5Zr (x + y=13, wt%) alloys were prepared by sand casting to investigate the effects of GdGd/Y ratio /Y ratioGd/Y ratio on the microstructuresMicrostructures and mechanical propertiesMechanical properties . The results show that GdGd/Y ratio /Y ratioGd/Y ratio had little influence on the grain size and the phase constitution of the microstructuresMicrostructures . However, the volume fraction of the second phase Mg24(GdGd/Y ratio , Y)5 in as-cast state increased, while that of the cubic phase (Y, GdGd/Y ratio )H2 in as-solutionized state almost unchanged with the decrease of GdGd/Y ratio /Y ratioGd/Y ratio . The uniaxial tension tests of the three alloys show that for both as-solutionized and as-aged states, the yield strength was slightly increased but the ductilityDuctility was apparently decreased with the decrease of GdGd/Y ratio /Y ratioGd/Y ratio from 3.33 to 1.17. It was thought that GdGd/Y ratio and Y atoms in Mg matrix have approximate solute strengthening effect but different adverse effect on ductilityDuctility , which should be responsible for the mechanical propertiesMechanical properties difference for the three alloys.

J. L. Li, D. Wu, R. S. Chen, En-Hou Han

Magnesium Technology 2019: Thermomechanical Processing

Frontmatter

Evolution of Heterogeneous Microstructure of Equal-Channel Angular Pressed Magnesium

This study investigated the distribution variations of the 0002 poles of magnesiumMagnesium after experienced a series of numbers of equal-channel angular pressingEqual channel angular pressing (ECAPECAP ) passes through either the Bc route or the C route. For the ECAPECAP processing, the mold channel angle was 142° and the sample temperature was 200 °C. The results show that most 0002 poles are in the ring of about 60–80° away from the ED for all ECAPed samples, and the location of the maximum intensity oscillates in the 60–80° range. The first ECAPECAP pass increased the nonuniformity of the distribution of 0002 poles, while the following ECAPECAP passes resulted in more uniform distribution of 0002 poles in the 60–80° ring and reduced textureTexture intensity through decreasing the maximum intensity and the intensity range of 0002 poles with the increase in the number of ECAPECAP passes for both Bc and C routes.

Qizhen Li

Novel Magnesium Alloy Processing via Shear-Assisted Processing and Extrusion (ShAPE)

Traditional magnesium alloyMagnesium Alloy manufacturing has often relied on processing within a temperature range that results in liquid phase formation of some of the constituents. These methods are often limited by the equilibrium phase formation states available from the melt. In this work, we will present findings on a recently developed processing approach that enables complex, unique microstructural evolution (often to persistent metastable states) while remaining in the solid phase state. Specifically, the shearShear assisted processing and extrusionExtrusion (ShAPEShAPE ) method as applied to Mg alloys will be presented. Novel microstructural pathways, textural formation and mechanical propertiesMechanical properties will be discussed. These results point to the ability to design and engineering novel Mg materials with unprecedented properties and performance.

S. Mathaudhu, N. Overman, S. Whalen, M. Olszta, D. Catalini, K. Kruska, J. Darsell, V. Joshi, X. Jiang, A. Devaraj, G. Grant

Effects of the Extrusion Temperature on Microstructure, Texture Evolution and Mechanical Properties of Extruded Mg–2.49Nd–1.82Gd–0.19Zn–0.4Zr Alloy

MicrostructureMicrostructure , texture evolutionTexture evolution and mechanical propertiesMechanical properties of extruded Mg–2.49Nd–1.82Gd Gd/Y ratio –0.19Zn–0.4Zr alloy were investigated at extrusionExtrusion temperatures of 260 °C, 280 °C, 300 °C and 320 °C, with an extrusionExtrusion ratio of 15 and RAM speed of 3 mm s−1, respectively. The results indicated that the coarse grains of homogenized billets were substantially refined after the extrusionExtrusion process, which was caused by the refinement of dynamically recrystallization (DRXDRX ) and the pinning effect of precipitated Mg5GdGd/Y ratio and Mg12(Nd, GdGd/Y ratio ) particles. The grain size decreased gradually when the extrusion temperatureExtrusion temperature increased from 260 to 280 and 300°C, and then coarsened slightly once the extrusion temperatureExtrusion temperature further increased to 320 °C. Moreover, the DRXDRX process was promoted with the increasing extrusion temperatureExtrusion temperature , and a completely DRXDRX microstructureMicrostructure could be obtained when the extrusion temperatureExtrusion temperature up to 300 °C. The room temperature tensile and compressive yield strength increased when the temperature increased from 260 to 300 °C and then decreased at 320 °C. All extruded alloys exhibited an extremely low tension–compression yield asymmetryTension-compression yield asymmetry , which was mainly attributed to the rare earth (RE) textureTexture component as well as the fine microstructureMicrostructure developed during the extrusionExtrusion process.

Lei Xiao, Guangyu Yang, Shifeng Luo, Wanqi Jie

Influence of Thermomechanical Treatment on Tension–Compression Yield Asymmetry of Extruded Mg–Zn–Ca Alloy

Thermomechanical treatment consisting of pre-compressionPre-compression and isothermal aging at 150 °C for 16 h was applied to the extruded Mg–Zn–Ca (ZX10) alloy in order to reduce tension–compression yield asymmetryTension-compression yield asymmetry and improve mechanical propertiesMechanical properties via strengthening mechanism. With respect to the initial textureTexture of the alloy, pre-compressionPre-compression leads to a formation of extension twins. A solute segregationSolute segregation and precipitationPrecipitation along twin boundaries is realized during a subsequent isothermal aging. After thermomechanical treatment, a solute solution and precipitation hardeningPrecipitation hardening contribute to the strengthening of the alloy. Active deformation mechanisms were monitored during compression or tension using the acoustic emissionAcoustic emission technique.

P. Dobroň, M. Hegedüs, J. Olejňák, D. Drozdenko, K. Horváth, J. Bohlen

Homogeneous Grain Refinement and Ductility Enhancement in AZ31B Magnesium Alloy Using Friction Stir Processing

Low ductilityDuctility in magnesiumMagnesium (Mg) alloy hinders its application in material forming industries. Hence, it is indeed of the material processing technique to modify the microstructureMicrostructure of Mg alloyMg alloy for increasing ductilityDuctility . Present work aims to refine the grain size of thick AZ31BAZ31B Mg alloyMg alloy using friction stir processingFriction stir processing (FSPFSP ) technique. A low heat input stationary shoulderStationary shoulder tooling system is used for processing heat sensitive Mg alloyMg alloy , exhibiting small temperature gradient across the thickness of processed material. This low heat input and small temperature gradient contributed to uniform grain refinementGrain refinement across the thickness due to dynamic recrystallization. Significant reduction in grain size achieved after FSPFSP , which helped to enhance the elongation of FSPFSP samples (top, middle, and bottom) in comparison with the unprocessed material. Furthermore, uniform and homogenous grain size and elongation obtained across the thickness of processed material, which was attributed to the stationary shoulderStationary shoulder tooling system.

Vivek Patel, Wenya Li, Quan Wen, Yu Su, Na Li

Microstructure and Texture Evolution During Hot Compression of Cast and Extruded AZ80 Magnesium Alloy

Uniaxial compression tests were conducted on cast and extruded AZ80Extruded AZ80 alloys at 400 °C and a strain rate of 0.1 s−1 up to a true strain of 1.0. MicrostructureMicrostructure and texture evolutionTexture evolution during hot deformation was studied using optical microscopy, X-ray diffraction macrotexture analysis and electron backscatter diffraction. The results indicate that dynamic recrystallization (DRXDRX ) occurred in the samples during deformation for both cast and extruded starting materials and the DRXDRX fraction was found to increase with deformation strain level. The DRXDRX grain size for both cast and extruded materials was measured as ~5 µm and was independent of the deformation strain. In both cast and extruded materials, hot deformation led to the development of a sharp basal textureTexture along the compression direction, which was attributed to grain rotation occurring during deformation, and preservation of deformation textureTexture by the DRXed grains.

Paresh Prakash, Amir Hadadzadeh, Sugrib Kumar Shaha, Mark A. Whitney, Mary A. Wells, Hamid Jahed, Bruce W. Williams

Experimental Investigation of Friction Coefficient of Magnesium Alloy Developed Through Friction Stir Processing with PKS Ash Powder Particles

MagnesiumMagnesium metal alloys have application in a variety of engineering field. The inclusion of a number of metal particles into pure magnesiumMagnesium to improve its properties has been on the rise. The method of inclusion has gone pass the conventional powder metallurgy or stir casting method. In the current study, friction stir processingFriction stir processing (FSPFSP ) was used for the embedment of palm kernel shell (PKS) ash particle into a magnesiumMagnesium substrate. MicrostructureMicrostructure analysis of the developed composite showed a well-distributed PKS ashPKS Ash particles into the magnesiumMagnesium metal matrix. The Vickers hardnessVickers Hardness test shows an improvement on the hardness of the developed surface composite, especially at the middle and end of the specimen with respective values of 62.65 and 63.27 when compared to that of the base metal. FrictionFriction test was done under various loading of 1 and 10 N at a constant speed and relative humidity of 70%. The results revealed mean coefficient of frictionFriction of 0.857 and 0.478 for 1 N and 10 N loads, respectively. Friction stir processingFriction stir processing proves to be an adequate technique of improving the surface properties of magnesium alloyMagnesium Alloy when using PKs ashPKS Ash powder as reinforcement.

R. S. Fono-Tamo, Esther Titilayo Akinlabi, Jen Tien-Chien

A Review and Case Study on Mechanical Properties and Microstructure Evolution in Magnesium–Steel Friction Stir Welding

Weight minimization and global environmental policies on carbon content open a new research avenue towards materials and manufacturing processes in transport industries. Friction stir weldingFriction stir welding (FSW) process is a combination of frictional heating and stirring action where materials are joined in their solid state. In this study, a review has been made on the joining status of magnesium alloysMagnesium alloys to steel by using FSW. Present problems and future opportunities of magnesiumMagnesium to steel joining with the help of FSW are also stated. A case study has also been presented where the joint characteristics of AZ31BAZ31B to AISI 304 sheets fabricated in lap configuration by FSW have been investigated by varying tool rotational speed (600, 1000, and 1800 rpm) and varying weld speed (40, 200, and 350 mm/min). A maximum weld joint efficiency of 79% of the AZ31BAZ31B base alloy has been achieved with a parametric combination of 600 rpm and 350 mm/min.

Suryakanta Sahu, Omkar Thorat, Raju Prasad Mahto, Surjya Kanta Pal, Prakash Srirangam

Effects of Sn on Microstructures and Mechanical Properties of As-Extruded Mg−6Al−1Ca−0.5Mn Magnesium Alloy

Effects of SnSn on microstructuresMicrostructures and mechanical propertiesMechanical properties of Mg–6Al–Ca–0.5Mn magnesium alloyMagnesium Alloy were investigated. With Sn addition, the grain size of Mg–6Al–Ca–0.5Mn–xSn alloy decreases and the volume fraction of Mg2Sn phase increases. The minimum average grain size of Mg–6Al–Ca–0.5Mn–xSn alloy is 15 μm. The distribution of the phase is more dispersive in the Mg matrix. SnSn content plays a key role for the inhibition of β-Mg17Al12 phase and the promotion of Mg2Sn phase. However, excessive SnSn addition results in the decline of strength and elongation. Tensile results show that the Mg–6Al–Ca–0.5Mn–3Sn alloy exhibits the best mechanical propertiesMechanical properties , and the ultimate tensile strength, yield strength and elongation of the alloy are 335.9 MPa, 261.1 MPa and 10.9%, respectively. The improved tensile properties are mainly related to grain refinementGrain refinement , solid solution strengthening of Sn and precipitationPrecipitation strengthening of Mg2Sn phase. Fractographic analysis demonstrates that quasi-cleavage fracture is the dominant mechanism of these alloys.

Huajie Wu, Ruizhi Wu, Daqing Fang, Yuesheng Chai, Chao Liang

Magnesium Technology 2019: Corrosion and Surface Protection

Frontmatter

Effect of Alloying with Rare-Earth Metals on the Degradation of Magnesium Alloys Studied Using a Combination of Isothermal Calorimetry and Pressure Measurements

With all the versatility in structural performance and recent progress in developing magnesium alloysMagnesium alloys , their Achilles heel remains to be degradationDegradation or corrosionCorrosion property. While applicationsApplications in mobility demand corrosionCorrosion protection by all means, bio-medical applicationsApplications of Mg alloysMg alloys require well-controlled degradationDegradation rates. Meeting these requirements is only possible through the understanding of phenomena on surface–environment interfaces and the characteristics of Mg alloysMg alloys affecting them. In this study, in situ monitoring during immersion testing along with 3D-optical and scanning-electron microscopy were used for assessing structure-performance characteristics. The effect of alloying with rare-earth metals on the degradationDegradation of magnesiumMagnesium has been studied in three model alloys Mg–0.8Nd, Mg–0.2Zr and Mg–2.0GdGd/Y ratio using a combination of isothermal calorimetryIsothermal calorimetry and pressure measurementsPressure measurements . The combination appears to be a powerful method to study corrosionCorrosion of magnesiumMagnesium . The degradationDegradation of the GdGd/Y ratio -containing alloy is approximately 100 times that of the other two alloys studied and is associated with the release of heat and hydrogen gas in large quantities. Differences in the morphology of corrosionCorrosion products on Mg–0.8Nd and Mg–0.2Zr alloy surfaces can be associated with minute variations in the degradationDegradation process detected by the developed method.

Lars Wadsö, Norbert Hort, Dmytro Orlov

Effects of Li on Microstructures and Corrosion Behaviors of Mg–Li–Al Alloys

The microstructuresMicrostructures and corrosionCorrosion behaviors of three Mg–Li–Al alloys are systemically investigated by changing the Li concentrations. The Al addition in the Mg–Li–Al alloys with different Li contents results in various intermetallic compounds: the AlLi formation in the Mg–3Li–6Al alloy as well as the AlLi and MgLiAl2 formation in the Mg–9Li–6Al and Mg–15Li–6Al alloys. The formation of AlLi and MgLiAl2 intermetallic compounds plays a significant role in the improvement of corrosion propertiesCorrosion properties . The corrosionCorrosion performance of the cast LA36, LA96, and LA156 samples can be ranked as LA96 > LA156 > LA36.

Yang Li, Tingchao Li, Qilong Wang, Yun Zou

Galvanically Graded Interface: A Computational Model for Mitigating Galvanic Corrosion Between Magnesium and Mild Steel

The impact of a graded metallic spacer on the galvanic corrosionCorrosion between magnesiumMagnesium and mild steel is investigated in this work using a COMSOL model based on a validated numerical model. A graded spacer of 4 mm thickness decreases the peak galvanic corrosionCorrosion by 50% over a system without a spacer, and 37% over a system with an aluminum spacer. The impact of the electrochemical properties of spacer materials is also investigated.

Kurt A. Spies, Vilayanur V. Viswanathan, Ayoub Soulami, Yuri Hovanski, Vineet V. Joshi

Iron Content in Relationship with Alloying Elements and Corrosion Behaviour of Mg3Al Alloys

In the present study, the effect of various alloying elements on controlling of iron content in magnesium alloysMagnesium alloys was investigated. A number of alloying elements including manganese, calcium, and yttrium were added separately and simultaneously to the melt then the iron content was determined. The effect of elements on iron removing was evaluated and compared. The results were interesting since it has changed the idea of considering manganese as the best to remove iron from the melt. Other elements would be a better candidate to improve the corrosionCorrosion resistance of magnesium alloysMagnesium alloys , especially yttrium due to its double effect on iron removing and forming of a protective film to protect the matrix. This study would contribute effectively to a design of high-performance magnesium alloysMagnesium alloys in the future.

Ha Ngoc Nguyen, Jong Il Kim, Young Min Kim, Bong Sun You

Microstructures, Corrosion and Mechanical Properties of Mg–Si Alloys as Biodegradable Implant Materials

Magnesium alloys attracted more and more attentions as biodegradable implant materials because of their properties similar to cortical bone. From the perspective of element biosafety and dietetics, the ideal alloying elements suitable for biodegradable applications should be those essential to or naturally presented in the human body. This study presents a novel aluminum-free magnesium alloy system with Si selected as a major alloying element, due to its superior biocompatibility in biological environment, especially in bone regeneration and repairment. Mg–Si binary alloys with different Si contents were prepared in a permanent mould via gravity casting and direct-chill casting. The microstructures, corrosion properties and mechanical properties were inves- tigated as a function of alloy composition.

Weidan Wang, Ming Gao, Yuanding Huang, Lili Tan, Ke Yang, Norbert Hort

The Influence of Temperature and Medium on Corrosion Response of ZE41 and EZ33

Mg-based implants offer a promising alternative to commonly used permanent implants due to their biodegradability that eliminates the need for a follow-up surgery, along with the associated medical and economic risks. Several of the commercial Mg alloysMg alloys for various applicationsApplications including potential implant applicationsApplications contain rare earth elements that are known to improve mechanical strength and corrosionCorrosion resistance. However, it remains a significant challenge to better understand in vitro corrosionCorrosion behavior of Mg–RE alloys and predict in vivo behavior, which is useful for biomedical applicationsApplications , since in vitro corrosionCorrosion rates tend to be significantly higher than those reported in vivo. In this work, we study the mechanical and corrosionCorrosion behavior of two Mg–RE alloys, ZE41 and EZ33, at physiologically relevant temperature of 37 °C in 3.5 wt% NaCl and Hank’s solution. Tensile and compression tests were used to evaluate mechanical propertiesMechanical properties while electrochemical techniques were used to investigate the corrosionCorrosion response. Both alloys demonstrated improved corrosionCorrosion resistance in Hank’s solution which was attributed to the formation of a more protective surface film. In addition, the increased RE concentration positively impacted the corrosionCorrosion behavior of EZ33 compared to ZE41 in both mediums.

M. AbdelGawad, A. U. Chaudhry, B. Mansoor

Alloy Design Strategies of the Native Anti-corrosion Magnesium Alloy

Application of Mg alloyMg alloy is limited because of its poor corrosionCorrosion resistance. Due to low standard electrode potential of Mg, severe galvanic corrosionCorrosion can happen if other alloyed elements form high electrode potential precipitate in Mg alloyMg alloy . Moreover, natively formed oxide film on the surface of pure Mg is not compact and cannot hinder further oxidation of inner substrate. In this work, alloy designAlloy design strategies are proposed to improve the native anti-corrosionAnti-corrosion property of Mg alloysMg alloys . The first is to purify the Mg-melt by forming high-density precipitates in the settling process to increase the efficiency of the settling process. The second is to enclose extra impurities in harmless compounds to avoid the severe galvanic corrosionCorrosion . The third is to control the composites of oxides formed on the surface by alloying defined elements to obtain passivate, close packing oxides film.

Tao Chen, Yuan Yuan, Jiajia Wu, Tingting Liu, Xianhua Chen, Aitao Tang, Fusheng Pan

Corrosion Bending Fatigue of RESOLOY® and WE43 Magnesium Alloy Wires

RESOLOYRESOLOY ®, a magnesiumMagnesium resorbable alloy based on Mg–Dy is the focus of this study. CorrosionCorrosion bending fatigueBending fatigue behavior of RESOLOYRESOLOY wires was investigated with WE43WE43 serving as a reference. Since these wires are developed for absorbable implant applicationsApplications like stents, clips and anastomotic nails, circulating Ringer solution of 37 °C was used to simulate body conditions. The alloys were first extruded and finally cold-drawn to a wire diameter of 500 µm. Both alloys show very fine grains. The microstructureMicrostructure of WE43WE43 was found homogeneous and equiaxed. RESOLOYRESOLOY shows recrystallized but non-equiaxed grains. RESOLOYRESOLOY is slightly harder than WE43WE43 . Both alloys were subjected to strain-controlled fatigue and corrosion fatigueCorrosion fatigue in a sequence which mimicked stent crimping, expansion, and in-vessel cycling. Fatigue life was strongly influenced by corrosionCorrosion . Fatigue data for RESOLOYRESOLOY highlight the need for further wire processing optimizationOptimization work that is currently underway.

Petra Maier, Adam Griebel, Matthias Jahn, Maximilian Bechly, Roman Menze, Benjamin Bittner, Jeremy Schaffer

Sacrificial Cathodic Protection of Mg Alloy AZ31B by an Mg–5Sn Surface Alloy

A solid solution Mg–5Sn alloy is evaluated as a sacrificial anode for the cathodic protectionCathodic protection of AZ31BAZ31B . Uncoupled Mg–5Sn is shown to have superior barrier properties and reduced cathodic kineticsKinetics relative to AZ31BAZ31B . The performance as a sacrificial anode was studied in situ with global and local measurements of galvanic coupling between the Mg–5Sn alloy and AZ31BAZ31B when immersed in 0.6-M aqueous NaCl solution. The scanning vibrating electrode technique (SVETSVET ) was utilized to map the local current density distributions across the interface of the galvanic couple. Undesirable polarity reversal was observed during the initial 10 h of immersion, after which protection was offered. A self-corrosionCorrosion rate of 52% was observed.

C. F. Glover, T. W. Cain, J. R. Scully

Magnesium Technology 2019: Fundamentals, Mechanical Behavior, Twinning, Plasticity, Texture and Fatigue I

Frontmatter

Evolution of the Intermetallic Particle Distribution in Thixomolded Magnesium Alloys

The spatial distribution of intermetallic particles in magnesium alloys is critical to achieve a favorable combination of mechanical properties. The initial microstructure of Thixomolded alloys, with a fine homogeneous grain structure and intermetallic particle distribution, results in particularly favorable behavior. However, the as-molded microstructure is far from equilibrium. In this manuscript, the Thixomolded structure is characterized before and after heat treatment using electron microscopy.

B. T. Anthony, B. G. Dowdell, V. M. Miller

Revealing the Role of Combined Loading on the Tension–Compression Asymmetry in a Textured AZ31 Magnesium Alloy

In wrought Mg alloys, such as AZ31 alloy, a strong basal texture is developed during the rolling process, which leads to a high tension–compression anisotropic behavior at room temperature and irrespective of deformation rate. This classic anisotropy mainly arises due to activation of different deformation modes such as slip versus twin.

C. Kale, S. Srinivasan, P. Haluai, K. N. Solanki

An Investigation of Detwinning Behavior of In-plane Compressed E-form Mg Alloy During the In Situ Tensile Test

In this study, we investigated the detwinningDetwinning phenomenon of in-plane compressed E-form magnesiumMagnesium (Mg) alloy sheet systematically using in situ tensile testIn-situ tensile test combined with electron backscattered diffraction (EBSDEBSD ) technique. MicrostructureMicrostructure and microtextureMicrotexture evolutions were analyzed at different tensile strains during the in situ tensile testIn-situ tensile test . The detwinningDetwinning phenomenon in E-form Mg alloyMg alloy was found to be linked to both twin boundary mobility and the interaction of their boundaries with dislocations. The pre-compressed sheet of E-form Mg alloyMg alloy effectively accommodated the thickness direction strains generated during the in situ tensile testIn-situ tensile test . The effect of detwinningDetwinning on formabilityFormability and mechanical behaviorMechanical Behavior of the E-form Mg alloyMg alloy was also examined. EBSDEBSD results indicate that most of the deformation twinsDeformation twins formed during in-plane compression were removed when the load is reversed during the in situ tensile testIn situ tensile test .

Jaiveer Singh, Min-Seong Kim, Seong-Eum Lee, Joo-Hee Kang, Shi-Hoon Choi

Characterization of Staggered Twin Formation in HCP Magnesium

Twins in hexagonal close-packed polycrystals, most often nucleate at grain-boundaries (GBs), propagate into the grain and terminate at opposing GBs. Regularly, multiple parallel twins of the same variant form inside the same grain. When twins terminate inside the grains, rather than the grain boundary, they tend to form a staggered structure. Whether a staggered twin structure or the more common grain spanning twin structure forms can greatly affect mechanical behaviorMechanical Behavior . In this work, the underlying mechanism for the formation of staggered twins is studied using an elasto-visco-plastic fast Fourier transform model, which quantifies the local stresses associated with $$ \left\{ {10\overline{1} 2} \right\} $$ -type staggered twins in magnesiumMagnesium for different configurations. The model results suggest that when a twin tip is close to the lateral side of another twin, the driving force for twin propagation is significantly reduced. As a result, the staggered twin structure forms.

M. Arul Kumar, B. Leu, P. Rottmann, I. J. Beyerlein

Dislocation Behavior and Grain Boundary Segregation of Mg–Zn Alloys

Mg–Zn solid solutions have been reported to show 14–21% tensile elongation after rollingRolling and annealing, but their textures exhibit strong basal textureTexture similar to pure Mg. This phenomenon contrasts with the case in Mg–Y solid solutions showing good RT ductilityDuctility and weakened basal textures. To reveal the mechanism of the good ductilityDuctility and strong basal textureTexture of Mg–Zn solid solutions at RT, we investigated the effect of Zn on Mg alloysMg alloys using atomistic simulations. The simulations show that Zn can activate <c + a> slip<c+a> slip by reducing critical resolved shearShear stress anisotropy among slip systems, thereby improving ductilityDuctility . It is also found that grain boundary segregationGrain boundary segregation tendency of Zn is low. The grain boundary segregationGrain boundary segregation is known to affect twinningTwinning and recrystallization which can modify the texture evolutionTexture evolution process. From the low grain boundary segregationGrain boundary segregation of Zn, Mg–Zn alloys are expected to yield a textureTexture similar to that of pure Mg.

Hyo-Sun Jang, Byeong-Joo Lee

Effect of Hot Working on the High Cycle Fatigue Behavior of WE43 Rare Earth Magnesium Alloy

Monotonic and cyclic behaviorCyclic behavior of the alloy WE43WE43 plates in two conditions is examined, with an emphasis on revealing microstructural features governing the differences in the behavior of the two plates. To facilitate the evaluation of the effect of hot working conditions on the behavior, the as-cast WE43WE43 was converted into two rolled plates with one being rolled at a temperature for 16.5 °C higher than the other plate. The plates were further processed into the T5 condition. The T5 plate rolled at a lower temperature was found to have a higher strength and elongation to fracture in tension. Additionally, it exhibited superior high cyclic fatigue behavior at room and elevated temperatures. The interesting performance characteristics of the alloy in two conditions are rationalized in terms of their microstructuresMicrostructures . The results reveal that it is possible to further optimize the hot working conditions to obtain the alloy exhibiting better performances.

Saeede Ghorbanpour, Brandon A. McWilliams, Marko Knezevic

Effect of Solute Atoms on the Twinning Deformation in Magnesium Alloys

Deformation twinningDeformation twinning is an important plastic deformation mode in magnesiumMagnesium and magnesium alloysMagnesium alloys . In this work, the solid solution hardening effectSolid solution hardening effect on the twinningTwinning deformation in Mg–Al binary alloys was investigated using molecular dynamicsMolecular dynamics (MD) simulations. In the MD modeling, we studied the effect of solute atom concentration on the nucleation stress and Peierls stress of twinningTwinning dislocations on the $$ \{ 10\bar{1} 2\} $$ extension twin boundary (TB). The simulation results show that the nucleation stress of twinningTwinning dislocations decreases as the concentration of solute atoms increases, indicating a solid solution softening effect. However, the Peierls stress increases with the increasing concentration of solute atoms, suggesting a hardening effect. So, the total effect of solute atoms on the twinningTwinning deformation depends on the competition between these two effects.

Jing Tang, Wentao Jiang, Xiaobao Tian, Haidong Fan

First-Principles Investigation of the Effect of Solutes on the Ideal Shear Resistance and Electronic Properties of Magnesium

Solute addition is an effective way to enhance mechanical propertiesMechanical properties , especially in magnesiumMagnesium based alloys due to the limited number of slip systems available for deformation at the room temperature. Hence, the effects of various alloying elements on ideal shear resistanceIdeal shear resistance (ISR) across different slip systems of Mg were investigated using first-principles calculations. The addition of a Ce, Y, or Zr solute atom was found to decrease ISR, whereas the substitution of a SnSn , Li, Al, or Zn atom increased the ISR of Mg. The most active slip system in Mg changed from the basal partial (0001) $$ \left[ {10\bar{1}0} \right] $$ to prismatic $$ (10\bar{1}0)[11\bar{2}0] $$ upon substitution of a Ce, Y, or Zr solute atom, whereas the addition of SnSn , Li, Al, or Zn solute atom had negligible effect on the plastic anisotropy. Furthermore, the electronic density of states and valence charge transfer provides a quantum insight into the underlying factors influencing the observed softening/strengthening behavior. For instance, the electronic density of states calculation shows that the contribution from d states of Ce, Y, and Zr solute atoms decreases the electronic structure stability of their respective solid solution, thereby enhancing slip activities. Theoretical analyses were also performed, and a shearability parameter was introduced to understand the implications of the observed variation in ideal shear resistanceIdeal shear resistance on the macroscopic behavior of Mg alloysMg alloys .

P. Garg, I. Adlakha, K. N. Solanki

Inverse Optimization to Design Processing Paths to Tailor Formability of Mg Alloys

Due to the poor formabilityFormability of Mg alloysMg alloys at low temperatures, robust methods are needed to intelligently tailor the formabilityFormability of Mg alloysMg alloys for given forming processes such that specific parts can be successfully manufactured. One method of tailoring formabilityFormability comes from altering the textureTexture of Mg alloysMg alloys . In our recent works, an invariant parameter called the Anisotropy Effect on DuctilityDuctility (AED) has been proven to correctly portray physical formabilityFormability measurements derived from tension and compression tests on textured AZ31 Mg alloyMg alloy . In the present work, a Visco-Plastic Self-Consistent (VPSCVisco Plastic Self Consistent (VPSC) model ) crystal plasticityCrystal plasticity modeling has been used to simulate Equal Channel Angular PressingEqual channel angular pressing as a processing method to alter textureTexture using various routes. In order to create an AZ31 Mg alloyMg alloy with a particular AED parameter or formabilityFormability , an automated inverse optimizationOptimization strategy has been used to predict the routes needed to attain target amount of formabilityFormability required by applicationsApplications .

Wahaz Nasim, Joshua S. Herrington, Amine A. Benzerga, Jyhwen Wang, Ibrahim Karaman

Magnesium Technology 2019: Fundamentals, Mechanical Behavior, Twinning, Plasticity, Texture and Fatigue II

Frontmatter

Recent Progress in Development and Applications of Mg Alloy Thermodynamic Database

Recent progress in the development of the thermodynamic database for multicomponent magnesium alloysMagnesium alloys , PanMg, is summarized and applicationsApplications are highlighted. PrecipitationPrecipitation simulations by combining thermodynamic and mobility databases for Mg alloysMg alloys with the PanPrecipitation module of Pandat are also summarized. These simulations can serve as virtual experiments to understand the effects of alloy composition and heat treatment condition on the target properties therefore providing guidance for the design of real experiments, saving time, and reducing cost. ApplicationsApplications of PanMg are exemplified in a wide spectrum of Mg alloyMg alloy design and related processing parameters, such as new creep resistant cast alloys, castability and hot-tearing susceptibility, semisolid metal processing, ductilityDuctility design and extrusionExtrusion , kineticsKinetics and precipitationPrecipitation simulation, low density high entropy alloys, corrosionCorrosion and recyclingRecycling alloys, and oxidation and surface design. The usefulness of the CALPHAD modeling tool in Mg technology is demonstrated in more detail for the selective high temperature oxidation of Mg alloysMg alloys using calculations with PanMg.

Rainer Schmid-Fetzer

Hardening Effects of Precipitates with Different Shapes on the Twinning in Magnesium Alloys

Molecular dynamicsMolecular dynamics (MD) simulations were performed to quantify the effect of the precipitate shapePrecipitate shape on the interactions with extension twin boundaries in magnesium alloysMagnesium alloys . Three precipitate shapes, including plate-, cube- and rod-like, were studied. The simulation results indicate that the blocking effect of plate-like precipitate is weakly affected by the precipitate aspect ratio (plate width/plate thickness; so, cube-like precipitate is at aspect ratio of 1), while the rod-like precipitate has a hardening effect decreasing with the increasing aspect ratio (rod length/rod width). This suggests that the plate-like precipitate has an identical hardening effect as the cube-like precipitate and a higher effect than the rod-like precipitate.

Haidong Fan, Jaafar A. El-Awady

Isometric Tilt Grain Boundaries and Solute Segregation in a Deformed Mg–Zn–Ca Alloy

Solute segregationSolute segregation to grain boundaries is an essential phenomenon that affects multiple mechanical propertiesMechanical properties of magnesium alloysMagnesium alloys . In this work, the deformed microstructureMicrostructure in a Mg–Zn–Ca alloy that was compressed at room temperature has been examined by bright-field and high-angle annular dark-field scanning transmission electron microscopy. Domains made of nanograins have been observed in some local areas. These domains exhibit strong textureTexture and most of the nanograins oriented with their $$ \left\langle {11\bar{2}0} \right\rangle_{\alpha } $$ being paralleled to each other, which is similar to those reported in the Mg–GdGd/Y ratio alloy. The grain boundaries of these nanograins involve many isometric tilt boundaries containing twin boundaries. Segregation of Zn/Ca atoms occurs in these tilt boundaries in the cold deformed sample. The segregation forms unique and chemically ordered patterns specific to tilt boundaries.

Y. M. Zhu, J. F. Nie

Metallography of Mg Alloys

Processing and composition determine microstructuralMicrostructure properties. To reveal the microstructureMicrostructure , the metallographic investigation is a commonly used method, and therefore, it is a crucial part in the characterizationCharacterization of metals and alloys. Choosing incorrect preparation steps will lead to artefactsArtefacts and misleading conclusions due to the compositional analysis and processing steps influencing the microstructureMicrostructure . However, in the published literature, it is obvious that not all reported microstructuresMicrostructures are in fact true microstructuresMicrostructures of investigated material. Especially in the case of magnesiumMagnesium and its alloys, special care is necessary to obtain micrographs with a true representation. What quite often is presented are surfaces that show artefactsArtefacts rather than microstructuresMicrostructures . Examples of this will be shown as well as their counterpart real microstructuresMicrostructures .

Norbert Hort, Victor Floss, Sarkis Gavras, Gert Wiese, Domonkos Tolnai

Microstructure and Mechanical Properties of High Shear Material Deposition of Rare Earth Magnesium Alloys WE43

In this work, microstructural characterizationCharacterization and mechanical propertiesMechanical properties are investigated for rare earth magnesium alloyMagnesium Alloy , WE43WE43 , manufactured via a high-shearShear deposition process. The unique solid-state manufacturing process deposits feedstock via a hollow nonconsumable rotating cylindrical tool, thereby generating heat and plastically deforming the feedstock through controlled pressure as successive layers are metallurgically bonded upon a substrate. In this research, dynamic recrystallization and grain refinementGrain refinement is characterized for the as-deposited WE43WE43 samples using Electron Backscattered Diffraction (EBSDEBSD ). The EBSDEBSD results for as-deposited WE43WE43 depict a refined grain structure formed by dynamic recrystallization (DRXDRX ). To quantify material properties, quasi-static tension tests were performed in three orthogonal directions to elucidate mechanical performance and isotropic behavior of as-deposited WE43WE43 .

Z. McClelland, D. Z. Avery, M. B. Williams, C. J. T. Mason, O. G. Rivera, C. Leah, P. G. Allison, J. B. Jordon, R. L. Martens, N. Hardwick

Modeling the 3D Plastic Anisotropy of a Magnesium Alloy Processed Using Severe Plastic Deformation

The mechanical response of magnesium AZ31 processed using severe plastic deformation is characterized using a two-surface, pressure-insensitive plasticity model. The model captures the 3D plastic anisotropy and the tension–compression asymmetry as the behavior evolves during straining. The model may be viewed as a reduced-orderReduced order model quasi-crystal plasticity model, whereby the two activation surfaces represent glide- and twinning-dominated flow. The two-surface formulation enables independent, yet coupled, hardening laws in terms of effective plastic strains accumulated on either generic deformation system. Material identification was completed using tension and compression specimens oriented along the principal directions of the processed material, E, L, and F, as well as off-axes specimens that bisected the principal planes E–F, L–F, and L–E. Using the nominal stress–strain and lateral strain data from the experiments, this model can capture the anisotropic behavior of this material.

J. S. Herrington, Y. Madi, J. Besson, A. A. Benzerga

Multiaxial Cyclic Response of Low Temperature Closed-Die Forged AZ31B Mg Alloy

The present study investigates the multiaxial fatigueMultiaxial Fatigue behavior of extruded AZ31BAZ31B Mg alloyMg alloy forged at 250 °C. Fatigue samples were tested under axial–shearShear loading at phase angles of 0°, 45° and 90°. The microstructural analysis identified dynamic recrystallization, which resulted in a degree of grain refinementGrain refinement of the forged microstructureMicrostructure in addition to a modification of the original extrusionExtrusion textureTexture . Quasi-static testing showed that the forged material retained the high yield strength of the extrusionExtrusion condition with a substantial increase in failure strain. Under multiaxial loading, cyclic axial strain significantly affected the shearShear hysteresis behavior while the effect of cyclic shearShear strain on the axial hysteresis was less pronounced. Despite a notable change in shearShear hysteresis shapeShAPE , fatigue life was only slightly affected by the changes in phase angle.

D. Toscano, S. K. Shaha, B. Behravesh, H. Jahed, B. Williams

Thermo-mechanical Processing of EZK Alloys in a Synchrotron Radiation Beam

Nd, a rare earth element with low solid solubility in Mg, is an ideal alloying element to improve elevated temperature yield strength and creep resistance cost effectively. The addition of Zn leads to further improvement in the elevated temperature properties; therefore, Mg–Nd–Zn alloysMg–Nd-Zn alloys are prospective materials for structural and medical applicationsApplications . In situ synchrotron radiation diffractionIn situ synchrotron radiation diffraction was performed during compression at 200 and 350 ℃ for Mg3NdxZn (x = 0, 0.5, 1, 2 wt%) alloys up to a deformation of 0.3 with a deformation rate of 10−3 s−1. The compressed samples were subsequently subjected to electron backscattered diffraction. The results show that at 200 ℃ the addition of Zn increased the ductilityDuctility . At the beginning of plastic deformation twinningDeformation twinning was the dominant deformation mechanism complemented by sub-grain formation at a later stage. At 350 ℃, the compression strength was increased with the addition of Zn and the microstructureMicrostructure of the samples underwent partial dynamic recrystallization during compression.

D. Tolnai, M.-A. Dupont, S. Gavras, K. Mathis, K. Horvath, A. Stark, N. Schell

The Effect of the Orientation of Second-Order Pyramidal  Dislocations on Plastic Flow in Magnesium

In this study, atomistic simulations are utilized to quantify the effect of the $$ \langle c + a\rangle $$ dislocation orientation on the critical resolved shear stress and mechanism of glide on second-order pyramidal planes in pure Mg. The studied orientations are those where the crystallographic periodicities along the dislocation line are less than about three times the $$ \langle c + a\rangle $$ Burgers vector magnitude. The simulations results show a sharply anisotropic response for the critical resolved shear with dislocation orientations, which indicates a much complex picture of plasticity in Mg than previously thought. The current results also show that the $$ \langle c + a\rangle $$ dislocations show a strong plastic anisotropic behavior and the second-order pyramidal slipPyramidal slip is limited by two singular mixed dislocation orientations at 16.78° and 42.13° with respect to the Burgers vector. Contrary to common understanding of dislocation behavior, $$ \langle c + a\rangle $$ slip in Mg is quite complex and coarse-grained models like DDD simulations that rely solely on edge and screw dislocation mobilities are therefore insufficient in capturing the plastic flow mechanisms.

Kinshuk Srivastava, Jaafar A. El-Awady

Magnesium Technology 2019: Poster Session

Frontmatter

Forging of Mg–3Sn–2Ca–0.4Al Alloy Assisted by Its Processing Map and Validation Through Analytical Modeling

The processing mapProcessing map for hot working of cast Mg–3Sn–2Ca–0.4Al (TXA320) alloy has been validated using forgingForging experiments to form a rib–web (cup) shaped component. Finite-element (FE) simulation has also been conducted to obtain the strain and strain rate variations in the components as well as the load–stroke curves. TXA320 has been successfully forged under optimum processing conditions (450 °C at press speeds of 1 and 0.1 mm s−1) predicted by the processing mapProcessing map , where dynamic recrystallization (DRXDRX ) occurs. The microstructureMicrostructure obtained on these components revealed fully DRXDRX grains and the average grain size has increased with increase in temperature. The load–stroke curves predicted by FE simulation of the forgingForging process correlate well with experimental curves, although the simulated curves are slightly lower. ForgingForging done in the flow instability regime of the processing mapProcessing map resulted in specimen fracture and the microstructureMicrostructure exhibited cracks at flow localization bands.

K. P. Rao, K. Suresh, Y. V. R. K. Prasad, C. Dharmendra, N. Hort

Development of Manufacturing Processes for Magnesium Sheet

Although casting is still the dominant manufacturing process of magnesiumMagnesium components, to open new application opportunities a quality sheet as a semi-finished product is required. At present, applicationsApplications for sheet have been limited due to the poor cold formabilityFormability of magnesiumMagnesium combined with the perceived high cost of the rolled products. In this report, research activities oriented towards development of advanced magnesium sheetMagnesium sheet technology at CanmetMATERIALS are described. They cover twin-roll castingTwin-roll casting and solid-state rollingRolling trials both conducted using the pilot-scale equipment. Results are presented for commercial alloys and experimental compositions with additions of rare earthsRare Earths , in-house designed and manufactured. The present challengesChallenges are outlined, including those caused by high affinity of magnesiumMagnesium to oxygen and their effect on hardware performance and quality of produced strips and sheets.

A. Javaid, F. Czerwinski

TMS-DGM Symposium on Lightweight Metals: Magnesium

Frontmatter

Incorporating an ICME Approach into Die-Cast Magnesium Alloy Component Design

The work presented here summarizes a methodology to incorporate an integrated computational materials engineering (ICME) approach into die-cast magnesium alloy component design. The framework of this approach was developed through process structure–property relationships developed through both Meridian’s internal and published studies.

J. P. Weiler

Influences of SiC Particle Additions on the Grain Refinement of Mg–Zn Alloys

A homogeneous microstructureMicrostructure of as-cast magnesium alloysMagnesium alloys is desired to improve their mechanical propertiesMechanical properties when achieving lightweighting. Recently, it was demonstrated that the addition of SiC refines both Mg–Al and Mg–Zn alloys. The present work investigates the effect of SiC particle additions on the grain refinementGrain refinement of Mg–Zn alloys, including their addition amount, particle size, addition temperature and holding time. The microstructuresMicrostructures were characterized using XRD, SEM and EDS. It was found that the addition of SiC particles refines the grains of Mg–Zn alloys. With increasing their amount and reducing the addition temperature and holding time, the grain size decreases. The optimal SiC particle size for nucleation of alpha-Mg was found to be around 2 µm. The responsible refinement mechanism is attributed to the formation of (Mn, Si)-enriched intermetallics by the interactions between SiC and impurity Mn in alloys.

Yuanding Huang, Jiang Gu, Sihang You, Karl Ulrich Kainer, Norbert Hort

Development, Characterization, Mechanical and Corrosion Behaviour Investigation of Multi-direction Forged Mg–Zn Alloy

In the present study, homogenized Mg−4%Zn (wt%) alloy was exposed to multi-direction forgingForging (MDF) at 280 °C up to 5 passes successfully. Microstructural evolution, mechanical propertiesMechanical properties and corrosionCorrosion behavior of the MDF-processed Mg−4%Zn alloyMg-4%Zn alloy was investigated using different characterizationCharacterization techniques. Five passes of MDF (cumulative strain, ΣΔε =  3.45) led to the formation of ultrafine grain structure (grain size ~2.3 μm) with high angle grain boundaries (HAGBs) and high dislocation density. Corresponding ultimate tensile strength (UTS) and microhardness were observed to be 228 MPa and 88 Hv. Potentiodynamic polarizationPotentiodynamic polarization test results exhibited higher corrosionCorrosion resistance (0.38 mm/y) in comparison with that of homogenized condition (1.33 mm/y).

Gajanan Anne, S. Ramesh, Goutham Kumar, Sandeep Sahu, M. R. Ramesh, H. Shivananda Nayaka, Shashibhushan Arya

Electrochemical Behaviour of ECAP-Processed AM Series Magnesium Alloy

Equal channel angular pressingEqual channel angular pressing (ECAPECAP ) is a technique for inducing high strain into the material to achieve ultrafine grain refinementGrain refinement . AM80AM80 magnesiumMagnesium was processed by ECAPECAP with processing route BC. ECAPECAP -processed samples were tested for microstructural studies and electrochemical measurementsElectrochemical measurements . Potentiodynamic polarizationPotentiodynamic polarization test revealed decrease in corrosionCorrosion current density due to uniform refined microstructureMicrostructure of the processed samples. Increment in charge transfer resistance (Rt) was observed for ECAPed samples with increase in capacitive arc diameters in Nyquist plots showing increased corrosionCorrosion resistance in comparison with as-cast condition. The increment in corrosionCorrosion resistance is because of grain refinementGrain refinement and uniform dispersal of intermetallic particles, which improved development of protective layer and bonding due to increased grain boundary density by ECAPECAP process.

K. R. Gopi, H. Shivananda Nayaka

Effect of Split Sleeve Cold Expansion on the Residual Stress, Texture and Fatigue Life of Rolled AZ31B Magnesium Alloy

In this study, the feasibility of the split sleeve cold expansionCold expansion of a wrought magnesium alloyMagnesium Alloy was investigated. The process includes radial expansion of the hole at room temperature, in which magnesium alloysMagnesium alloys exhibit limited formabilityFormability . The process has been successfully introduced in the rolled AZ31BAZ31B Mg sheet, and a preliminary evaluation of fatigue performance showed a significant improvement for the cold expanded hole compared to that of the starting condition. The microstructural analysis shows that microstructureMicrostructure near the hole is accommodating expansion through texture evolutionTexture evolution and grain refinements (i.e. elongated grains). The aggressive formation of twins within the grains near the hole surface is believed to be the main hardening mechanism in the very recent vicinity of the notch, where the maximum hardness was achieved. This mechanism alongside the compressive residual stress induced by the cold expansionCold expansion process delayed crack initiation and suppressed crack propagation leading to high fatigue lives.

S. Faghih, S. K. Shaha, S. B. Behravesh, H. Jahed

A Theory for Designing Ductile Materials with Anisotropy

A predictive theory is presented which enables projections of relative ductility and toughness in a wide class of anisotropic materials. Qualitative, and potentially quantitative, trends for stress-state-dependent ductility and fracture toughness are obtained with no experimental input other than the basic stress–strain curves, evidence of failure by progressive cavitation, and basic information about the inclusion content. A key concept is the anisotropy-effect-on-ductility (AED) index, which correlates complex three-dimensional anisotropy attributes of a material to a single scalar index of ductility and toughness. This index has a fundamental meaning as it emerges from a scale transition operation by means of micromechanics. A proof of concept is presented. The theory is relevant to lightweight metals whose anisotropy is inherent (Mg, Al), and eventually induced by processing (sheet metal). It is also relevant to additively manufactured metals where both porosity and process-induced anisotropy seem unavoidable so that the theory is useful in ductility–strength–cost tradeoffs.

A. A. Benzerga

Backmatter

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