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About this book

This proceedings volume gathers selected papers presented at the Chinese Materials Conference 2017 (CMC2017), held in Yinchuan City, Ningxia, China, on July 06-12, 2017.

This book covers a wide range of powder metallurgy, high performance aluminum alloys, high performance titanium & titanium alloys, superalloys, metal matrix composite, space materials science and technology, rare metals, refractory metals and their applications, advanced ceramics materials, nanostructured metals and alloys.

The Chinese Materials Conference (CMC) is the most important serial conference of the Chinese Materials Research Society (C-MRS) and has been held each year since the early 1990s. The 2017 installment included 37 Symposia covering four fields: Advances in energy and environmental materials; High performance structural materials; Fundamental research on materials; and Advanced functional materials. More than 5500 participants attended the congress, and the organizers received more than 700 technical papers. Based on the recommendations of symposium organizers and after peer reviewing, 490 papers have been included in the present proceedings, which showcase the latest original research results in the field of materials, achieved by more than 300 research groups at various universities and research institutes.

Table of Contents

Frontmatter

Effects of Internal Oxidation Methods on Microstructures and Properties of Al2O3 Dispersion-Strengthened Copper Alloys

Abstract
With Cu–Al alloy powder as raw material and Cu2O powder as oxidant, two internal oxidation methods, namely step-by-step internal oxidation-reduction method (referred to as the step-by-step method) and integrated internal oxidation-reduction method (referred to as the integrated method), were respectively adopted to achieve the oxidation of Al. Then hot extrusion without canning was applied to prepare Al2O3 dispersion-strengthened copper alloys. The effects of the two internal oxidation methods on microstructures and properties of the alloys were compared. The results show that both the step-by-step method and the integrated method can achieve the complete oxidation of Al. However, the excessive oxidant can not be reduced thoroughly in the integrated method. The residual oxidant increases oxidation of the sintered body during hot extrusion and the formed copper oxides distribute in the grains as well as at the grain boundaries. While in the step-by-step alloy, the copper oxides mainly distribute at the grain boundaries. The step-by-step method improves electrical conductivity and ductility, but lowers hardness and strength. The integrated alloy has worse ductility and lower electrical conductivity, but strength and hardness are higher. The step-by-step alloy has better comprehensive properties, and its electrical conductivity, hardness, tensile strength, yield strength and elongation is 89% IACS, HRB 69–72, 425 MPa, 394 MPa and 27.2%, respectively.
Feng Chen, Zhiqiao Yan, Tao Wang

Effects of Al Content on the Physical Properties of Al2O3 Dispersion-Strengthened Copper Alloys

Abstract
Based on three kinds of CuAl alloy powders with Al mass fraction of 0.18, 0.55 and 1.95%, respectively, as raw materials and Cu2O powder as oxidant, three dispersion-strengthened copper alloy powders with Al2O3 content of 0.34, 1.00 and 3.19%, respectively, were prepared by internal oxidation using the optimal internal oxidation parameter. Hot pressing was subsequently adopted to prepare Al2O3 dispersion-strengthened copper (Cu–Al2O3) alloys. The effects of Al2O3 content on microstructures and properties of alloy powders and sintered alloys were studied. The results showed that the microhardness of three alloy powders after internal oxidation was significantly improved and increased with increasing Al2O3 content. But the difference between powders with 1.00 and 3.19% Al2O3 content was small. The relative densities of sintered alloys with lower Al2O3 content, i.e. 0.34 and 1.00%, were both above 99%. However that with higher Al2O3 content, i.e. 3.19%, was only 97.8%. With increasing Al2O3 content, electrical conductivity decreased and hardness increased obviously. The electrical conductivity and hardness (HRB) of three alloys were 86.0, 71.5, 60.0% IACS, and 68.8, 84.3, 91.0, respectively.
Zhiqiao Yan, Feng Chen, Tao Wang

Synthesis of Beryllium Pebbles Using Plasma Rotating Electrode Process

Abstract
Beryllium is used as neutron multiplier in the form of a pebble bed. Basic characteristics of the beryllium pebbles are required to the design of blanket. From this point view, production methods and basic characteristics including particle morphology and mechanical properties of beryllium pebbles were investigated. The paper gives a brief description of fabrication technology for the Be pebbles. The Plasma Rotating Electrode Process (PREP) is the method for producing 1–1.2 mm Be pebbles for use as a neutron multiplier. The obtained results indicate the advantages for the fabrication of Be pebbles and the excellent properties of the pebbles.
Yumei Jia, Yongjin Feng, Jianli Zhang, Pingping Liu, Qian Zhan, Farong Wan

Preparation and Characterization of Fine 316L Stainless Steel Powders Prepared by Gas Atomization

Abstract
Atomization technique has the powder production advantages of high production efficiency, low cost and good sphericity. In this paper, 316L stainless steel powders were prepared in nitrogen atmosphere by using self-designed nozzles. The fine powders yield, particle size distribution, particle shape and microstructure of powders prepared by different nozzles and different pressure were studied. Particle analyzer was used to characterize the powders. Results show that the powders produced by more complex nozzle structures and higher pressure have higher yield and better effect sphericity. The slender powders are fewer. The average elongation is below 0.4, and the average O.Bluntness values are above 0.6. With the decrease of pressure, the average of O.Bluntness value increases and the sphericity of powders is improved. The average outgrowth values are below 0.2, and the satellite powders are lesser when the pressure is greater. The flowability of the 316L stainless steel powders prepared by lower pressure were better, while the powders prepared by the higher pressure have extremely poor fluidity. The fluidity was significantly improved after sieving the fine powders less than 25 µm. The surface and the internal microstructure of 316L stainless steel powders prepared by different processes are mainly cellular and dendrite structures.
Yingying Chen, Zhiyu Xiao, Haiping Zou, Shangkui Li, Aihong Li

Microstructure and Mechanical Properties of 1.2709 Die Steel by Selective Laser Melting

Abstract
The differences of microstructure and mechanical properties of die steel (1.2709) prepared by selection of laser melting (SLM) process and traditional casting-forging process were studied. Sample A was prepared by SLM process. Sample B was prepared by mixing process (half volume using conventional casting—half volume of forging process application SLM). Sample C was prepared by traditional casting–forging process. Three sets of samples were subjected to the same process of solution treatment and aging treatment. The microstructures and mechanical properties of the three groups were studied. The results showed that the microstructure of sample A was a homogeneous and dense plate-like martensite structure, and they were different in phase distribution. The microstructure observation of sample B indicated that the part of the conventional casting-forging process consisted of martensite and carbide particles, but the SLM process consisted of a uniformly distributed elongated martensite structure. In the region of different forming process, there was a transition region with a width of 40 μm. The transition zone was relatively loose and the defects were relatively more. The microstructure of conventional casting–forging process 1.2709 die steel samples was mainly composed of lath martensite and carbide particles. In addition, the relative densities of the three sets of samples were close to 100%. The impact toughness values αKV, αKU and the impact absorbing energy KV2, KU2 of sample B, sample A and sample C showed an increasing trend, and the mechanical property difference was less than 15%. It is proved that the mechanical properties of 1.2709 die steel workpiece prepared by SLM process can meet the needs of engineering application.
Mingyue Zheng, Shaoming Zhang, Jun Xu, Jinhui Zhang, Qiang Hu, Huijun He, Xinming Zhao

A Comparative Corrosion Study on Traditional and Melt-Spinning 7075 Al Alloy

Abstract
Rapidly solidified 7075 Al alloy ribbons were prepared by melt-spinning. Sintered 7075 compacts with fine-grain microstructure were obtained by spark plasma sintering of the chopped melt-spun ribbons at different sintering temperatures. The corrosion behavior of the sintered 7075 alloy was examined and compared to that of the 7075-T6 bulk by electrochemical and immersion experiments carried out in NaCl solution. Microstructures of the consolidated samples before and after corrosion tests were examined by optical microscope and scanning electron microscope. Ratios of corrosion after immersion tests were measured by an image analyzing software. Results of this study suggest that the sintered material exhibited slightly poorer corrosion resistance than the bulk 7075 alloy and the porosity adversely affect the corrosion behaviors of the sintered material.
Sieglind Ngai, Tungwai Ngai, Yongliang Ou, Weipeng Zhang, Liejun Li

Preparation of Fe/Fe3O4 Soft Magnetic Composites by Spark Plasma Sintering

Abstract
Fe/Fe3O4 soft magnetic composite was prepared with the method of physical coating method by spark plasma sintering. In this way, its sintering interface was improved. It solved the problem that hot pressing curing soft magnetic composites have low densification. The Fe/Fe3O4 was observed at different sintering temperatures and the influence of the chemical composition and microstructure properties was analyzed. The material density was higher and interface was combined with high performance. The resistivity decreases because the element changed with higher temperature. The morphology and structure are characterized by SEM, EDS and XRD, respectively and the electric properties are tested. In the end part we discuss the pros and cons of SPS method on synthesizing Fe/Fe3O4 soft magnetic composites and its potential application in industries.
Shuhan Lu, Jihang Ren, Zhankui Zhao

High-Quality Ti–6Al–4V Alloy Powder Prepared by Plasma Rotating Electrode Process and Its Processibility in Hot Isostatic Pressing

Abstract
High quality Ti–6Al–4V alloy powders were prepared by plasma rotating electrode process (PREP). Three different rotating speed were selected. After sieved, three kinds of powder with different size distribution were consolidated by hot isostatic pressing (HIP). The phase compositions, morphologies and microstructures of the powders and HIPed samples were characterized. Mechanical properties of HIPed Ti–6Al–4V alloys also were investigated. The results showed that the proportion of small particles increased with the increasing rotating speed. Alloy prepared by powders distributed in 100–150 μm possesses the best mechanical properties.
Liming Zou, Xin Liu, Huanwen Xie, Xinhua Mao

Microstructure and Mechanical Properties of Hot-Rolled 5E83 Alloy

Abstract
Hot-rolling plates of Al–4.5Mg–0.7Mn–0.2Zr–0.2Er alloy were prepared under the reduction of 50%, and tensile property, impact toughness were measured at the temperatures varying from 200–470 °C. The microstructure of the hot-rolling plates was investigated using scanning electron microscopy and transmission electron microscopy. The results showed that the tensile strength and yield strength decreased with the rise of the hot-rolling temperature, the elongation and impact toughness showed the opposite trend, and the best match between strength and toughness was at the rolling temperature of 350 °C. The second phase particles in the alloy had a great influence on the impact toughness and plasticity of the alloy. As the rolling temperature increased, the dynamic recovery and dynamic recrystallization occurred in the alloy. Dispersed Al3(Er, Zr) particles formed in the alloy when Er and Zr were added. The Al3(Er, Zr) particles were able to pin dislocation motion, hinder the growth of subgrains and the migration of grain boundaries, thereby inhibited the dynamic recrystallization of Al–4.5Mg–0.7Mn–0.2Zr–0.2Er alloy and its thermal stability improved.
Xin Li, Wei Wang, Hui Huang, Xiaoli Liu, Yifei Liu, Hongbo Wang, Shengping Wen, Xiaolan Wu, Kunyuan Gao, Zuoren Nie

Microstructure and Properties of Spray-Formed Si–30Al Alloy Used for Electronic Packaging

Abstract
The microstructure and properties of spray-formed Si–30Al alloy was studied in this paper, which was used for electronic packaging. Hot isostatic pressing was used to compact the ingot, and then electroplating and brazing was carried out. The results showed that, (1) the Si–30Al alloy comprised α-Al phase, pseudo eutectic phase and primary silicon phase; (2) the flow deformation of α-Al phase and pseudo eutectic phase filled pore defect making the alloy compacting by HIP; (3) the alloy could be electroplated and brazed easily, and no pore defect was observed in electroplated coating and weld.
Hongwei Liu, Shuhui Huang, Zhihui Li, Baiqing Xiong, Yongan Zhang, Xiwu Li, Hongwei Yan, Lizhen Yan

Effect of Erbium–Zirconium Composite Modifications on the Microstructure and Mechanical Properties of A356 Aluminum Alloy

Abstract
The Al–7Si–0.3 Mg (A356) alloys with various contents of the rare earth element Er, Zr were prepared by the conventional casting technique. The effect of Er, Zr composite modifications on the microstructure and mechanical properties of A356 alloys was investigated using the optical microscopy (OM), scanning electronic microscopy (SEM), energy spectrum analysis and mechanical testing. The results show that addition of 0.3 wt% Er and Zr had an excellent refining effect on α-Al grains and a modification effect on Si containing phase in the as-cast state. The size of α-Al dendrite reduced, the acicular eutectic Si became short rod-shaped or granular. When Er and Zr content was 0.3 wt%, the tensile strength and hardness of the alloys reached up to maximum values.
Liantao Ji, Wei Wang, Hui Huang, Shengping Wen, Kunyuan Gao, Xiaolan Wu

Modeling and Simulation of Dynamic Recrystallization Behaviors of 7085 Aluminum Alloy During Hot Deformation Using Cellular Automata Method

Abstract
Cellular Automata (CA) method can be used to simulate the microstructure evolution. The parameters of the CA model and thermal deformation parameters are input to the CA model as important data. The hot deformation behavior was studied by means of a hot simulating test on Geleeble-1500 experiment machine. The range of thermal deformation temperature is 623–723 K, the range of strain rate is 0.001–1 s−1 and the maximum true strain is 0.91. Analysis of microstructure of average grain size and recrystallization fraction by optical microscope (OM) and electron backscatter diffraction (EBSD). CA model was used to study the effects of strain, strain rate and deformation temperature on the deformed microstructure. The simulation results are validated by a great deal of experimental data, the simulation results are in good agreement with the experimental data that shows the feasibility and predictability of the CA method.
Jie Zhang, Zhihui Li, Shuhui Huang, Xiwu Li, Lizhen Yan, Hongwei Yan, Hongwei Liu, Yongan Zhang, Baiqing Xiong

Aging Time on the Microstructure and Mechanical Properties of A356 Alloy by Semi-solid Processing

Abstract
An investigation was carried out to study the effects of aging time on the microstructure and mechanical properties of A356 alloy by semi-solid processing. The alloy was subjected to solution treatment for 4 h at 540 °C, artificial ageing was carried out at temperature (170 °C) and different time (0–24 h). The results revealed that the needle-shaped eutectic Si phase in as-cast ingot was transformed to globular shape compared with that by solution treatment. Meanwhile the Chinese script π-Fe(AlMgSiFe) phase was transformed to smaller and uniformly distributed β-Fe(AlFeSi) phase, the elongation increased obviously. With the increasing of aging time, the elongation decreased, and the ultimate tensile strength increased. When the aging time was 4 h, the alloy achieved the optimal mechanical properties. The micro-hardness was 121HV, ultimate tensile strength was 329 MPa, and the elongation was 15%. From the fracture morphology, the fracture for alloy aging for 4 h showed more dimples. With the increasing of aging time, the ultimate tensile strength and the elongation decreased.
Peng Qi, Bolong Li, Wenjian Lv, Shasha Dong, Tongbo Wang, Ning Li, Zuoren Nie

Homogenization Treatment and Kinetic Analysis of 2297 Al–Li Alloy

Abstract
The microstructure evolution and composition distribution of the industrially cast 2297 Al–Li alloy during single-stage and double-stage homogenization were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and differential scanning calorimetry (DSC). The results show that severe dendrite segregation exists in the as-cast alloy. Cu, Fe and Mn elements have obvious segregation at grain boundaries, and the degree of enrichment decreases gradually from grain boundary to intracrystal. The undissolved phases in the grain boundaries are mainly Al2Cu phase and Fe and Mn containing phase. The optimal single-stage homogenization treatment system is 525 °C × 24 h. And the optimal double-stage homogenization system is 460 °C × 20 h + 525 °C × 24 h. After double-stage homogenization treatment, non-equilibrium eutectic phase on the grain boundary fully dissolved, and the segregation of dendrite is eliminated. At the same time, the size of Al3Zr particles is uniform and distributed dispersion, while no dissolved Fe and Mn containing phase is found at grain boundaries. The mechanism of the double-stage homogenization treatment agrees with the results of kinetic analysis.
ShengLi Yang, Jian Shen, Peng Jiang, PeiYue Li, Yan Yu, DeJun Song, Huan Tao, Wei Guo, Wen Fu

The Microstructure Evolution of Al–Mg–Si–Mn–Er–Zr Alloy During Homogenization

Abstract
The formation of non-equilibrium intermetallic phases during solidification significantly deteriorates the mechanical properties of Al–Mg–Si–Mn–Zr–Er alloy, but homogenization heat treatment can effectively reduce these residual phases. Therefore, it is necessary to study the evolution of these non-equilibrium intermetallic phases during different homogenization treatment. In this study, the methods we used are OM, SEM in combination with EDS, XRD and TEM. The results showed that non-equilibrium intermetallic phases between grains are mainly Al0.5Fe3Si0.5, Al0.7Fe3Si0.3 and Al5Mn12Si7. After homogenization, the main residual phase is Al5Mn12Si7. Compared with single homogenization, two-stage homogenization can effectively reduce the homogenization time and is good for the precipitation of fined Al3(Er, Zr) particles.
Xiang Zhang, Hui Huang, Xiaoli Liu, Yifei Liu, Hongbo Wang, Shengping Wen, Kunyuan Gao, Xiaolan Wu

Effect of Intermediate Annealing Temperature and Aging on the Mechanical Properties and Conductivity of Al–0.2Mg–0.35Si–0.3Ce Wire Rod

Abstract
The present study investigated the effect of intermediate annealing temperatures on the microstructure, mechanical properties and conductivity of Al–0.2Mg–0.35Si–0.3Ce wire rod, which experienced hot extrusion (named as E), cold drawing (named as D), annealing (named as A) and cold drawing, i.e. EDAD. And four intermediate annealing temperatures (150, 200, 250, 300 °C) were carried out for investigation. Microstructure observation shows that no recrystallization occurs in the wire rod when annealed at 150 and 200 °C. However, it occurs when the annealing temperature reaches 250 °C. Tensile tests indicate that the ultimate tensile strength (UTS) of the as-EDAD samples firstly increases to a maximum value of 218 Mpa when the annealing temperature increased to 150 °C, and then decreases dramatically with the temperature continuously increasing. However, the elongation and conductivity of the as-EDAD samples just go oppositely. The conductivity of the sample annealed at 300 °C reaches 57.1%IACS, which is about 3.3%IACS higher than that of the sample without annealing. The effect of aging (190 °C for 20 h) on the mechanical properties and conductivity of as-EDAD samples was also investigated. Results show that the variation trend of UTS, elongation and conductivity of the EDAD-aging samples is similar to that without aging. The UTS decreases after aging, however, elongation and conductivity both increase.
Yuna Wu, Hengcheng Liao, Jianfeng Zhang

Quantitative Investigation of Precipitates in a High-Zinc Al–9.54Zn–2.10Mg–1.69Cu Alloy with Various Typical Tempers

Abstract
In order to analyze single stage ageing behavior of a high-zinc Al–9.54Zn–2.10Mg–1.69Cu alloy, the microstructure of the alloy subjected to T6, T76 and T77 states are investigated via transmission electron microscopy (TEM) combined with high-resolution transmission electron microscopy (HRTEM) attached to it. Under the premise in precipitate observations, diameter distributions and average diameter size of precipitates are deduced from Bright-Field TEM (BF TEM) images projected along \( \left\langle {110} \right\rangle_{\text{Al}} \) orientation with the help of an image processing. The results indicate that the main precipitates are GPII zone and η′ phase in the T6 and T77 alloys while η′ and η phase in the T74 alloy. The Bright field TEM observations reveal that the matrix precipitates for the T6 and T77 alloys have small size and dispersive distribution while that for the T74 alloy has big size and sparse distribution. Quantitative precipitate characteristics including diameter distribution and average diameter size have been gained by an image processing relying on BF TEM images projected along \( \left\langle {110} \right\rangle_{\text{Al}} \) orientation. The results reveal that the T6 and T77 alloys have more than a half percentage of precipitates with a size less than 2 nm while the T77 and T74 alloys have broad precipitate distribution range till 14 and 16 nm, respectively. The grain boundary precipitates (GBPs) for the T6 alloy have continuous distribution with small size while that for the T74 and T77 alloys distribute intermittently with big size.
Kai Wen, Bai-Qing Xiong, Yong-An Zhang, Xi-Wu Li, Zhi-Hui Li, Shu-Hui Huang, Li-Zhen Yan, Hong-Wei Yan, Hong-Wei Liu

Flow Behaviors and Corresponding Constitutive Equation of the Al–9.4Zn–1.9Mg–2.0Cu Alloy

Abstract
Isothermal compression tests of the Al–9.4Zn–1.9Mg–2.0Cu alloy were carried out at the temperature ranging from 300 to 460 °C and the strain rate from 0.001 to 10 s−1, and the deformation degree was 70%. Flow stress curves show that the flow stress decreases with the increasing deformation temperature and the decreasing strain rate. The measured flow stress was corrected because of the effect of friction. The corresponding corrected stress values are lower than measured stress values. The effect of friction is far greater when hot-deformations occurred at lower temperatures or higher strain rates. A constitutive equation considering the effect of strain on material constants (i.e. α, n, Q and A) are established based on the Arrhenius-type equation. Compared with the experimental results, the flow stresses calculated by the constitutive equation have a high precision with the correlation coefficient of 0.95. Results show that higher deformation temperatures and lower strain rates are beneficial for hot deformation of the Al–9.39Zn–1.92Mg–1.98Cu alloy.
Guohui Shi, Yong’an Zhang, Xiwu Li, Zhihui Li, Shuhui Huang, Lizhen Yan, Hongwei Yan, Hongwei Liu

Effect of RRA Treatment on the Properties and Microstructural Evolution of Al–Zn–Mg–Cu–Er–Zr Alloy

Abstract
Effect of RRA treatment on the mechanical properties and microstructure of Al–Zn–Mg–Cu–Er–Zr aluminium alloy was researched by hardness measurement, conductivity measurement, exfoliation corrosion measurement, transmission electron microscopy (TEM). Discussed the relationship between the regression treatment and composite properties of the alloy. The study found that the hardness of RRA treated alloys first rise and then decline with the increasing of regression time, but the corrosion performance is increasing all the time. After pre-aging treatment 120 °C/24 h, regression treatment 180 °C/60 min, re-aging treatment 120 °C/24 h, the combination property of the alloy is optimal, the hardness, conductivity and the exfoliation corrosion grade are respectively: 207.6 HV, 33.53%IACS, PC. At this moment, it is found from the TEM observations that the matrix precipitates are small and dispersed, resemble to T6 temper. The grain boundary precipitation out phases are discontinuous distribution and the relatively wider PFZ, similar to the T73 temper.
Xiaofei Wang, Zuoren Nie, Hui Huang, Shengping Wen, Kunyuan Gao, Xiaolan Wu
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