Effects of silicon carbide reinforcement on microstructure and properties of cast Al–Si–Fe/SiC particulate composites

doi:10.1016/j.msea.2006.11.030

Materials Science and Engineering: A

Volume 447, Issues 1–2, 25 February 2007, Pages 355-360

https://doi.org/10.1016/j.msea.2006.11.030 Get rights and content

Abstract

The effects of silicon carbide (SiC) particles on the as-cast microstructure and properties of Al–Si–Fe alloy composites produced by double stir-casting method have been studied. A total of 5–25 wt% silicon carbide particles were added. The microstructure of the alloy particulate composites produced was examined, the physical and mechanical properties measured include: densities, porosity, ultimate tensile strength, yield strength, hardness values and impact energy. The results revealed that, addition of silicon carbide reinforcement, increased the hardness values and apparent porosity by 75 and 39%, respectively, and decreased the density and impact energy by 1.08 and 15%, respectively, as the weight percent of silicon carbide increases in the alloy. The yield strength and ultimate tensile strength increased by 26.25 and 25% up to a maximum of 20% silicon carbide addition, respectively. These increases in strength and hardness values are attributed to the distribution of hard and brittle ceramic phases in the ductile metal matrix. The microstructure obtained reveals a dark ceramic and white metal phases, which resulted into increase in the dislocation density at the particles–matrix interfaces. These results show that better properties is achievable by addition of silicon carbide to Al–Si–Fe alloy.

Introduction

In the last two decades most research and development efforts have aimed at reinforcing monolithic metals and alloys with a ceramic phase with the primary purpose of enhancing their properties, spanning the domains of physical, mechanical and fracture behaviour [1], [2] and strong interest has been shown in the application of metal matrix composites (MMCs) in the design of many engineering and non-engineering cornponents [3], [4].

Potential uses of these materials are numerous in industries and they include such areas of application as aerospace (satellite struts), defense (electronic instrument racks), automotive (drive shafts and brake discs), sports goods (golf clubs and mountain bicycle frames), and marine (yacht fittings) [5], [6]. When compared with the unreinforced matrix alloy, MMCs in general have superior mechanical properties, such as: high strength, high stiffness, high wear resistance, and very good elevated temperature properties. These properties can be tailored to meet specific requirements [7].

The early work on MMCs focused mainly on continuous fiber reinforcement. However, high cost of fibers, complex fabrication techniques, and limited fabricability restricted their use to those applications where the end could justify the means [8]. This opened the way for the development of low cost discontinuously reinforced MMCs, such as particle-reinforced MMCs [9], [10].

silicon carbide particles have become one of the popular reinforcing phases for many aluminum alloy-based metal matrix composites. They are hard and brittle ceramic particles with high strength, high modulus of elasticity, and high thermal and electrical resistance. The size of the particles depends on both the manufacturer and the type of alloy. However, the mean particle dimension normally lies in the range 2–20 μm [6].

Particle-reinforced MMCs are produced via various routes. They have additional advantages over the continuous fiber-reinforced MMCs especially since they are low-priced and have both high heat treatment ability and processing flexibility. Particle-reinforced MMCs are now being produced commercially [10], [11].

One of the factors limiting the use of MMCs for engineering components is a lack of property characterization in relation to the unreinforced alloys. The lack of data extends from processing parameters to final mechanical properties. Understanding the factors that influence the physical and mechanical properties of these materials is very important in the sense that these properties are sensitive to the type of reinforcement, the mode of production and the details of post-production processing [6].

The objectives of the present work are therefore to investigate microstructure and properties of as-cast Al–Si–Fe alloy and its composites reinforced with silicon carbide particles.

Section snippets

Specimen preparation

The synthesis of the metal matrix composite that was use in this study was produced using double stir-casting method at the Foundry Shop of the National Metallurgical Development Center, Jos, Nigeria. The specimens were produced by keeping the percentage of iron and silicon constant and varying the reinforcing material (silicon carbide) particles in the range 5–25% SiC. High purity aluminium electrical wires obtained from Northern Cable Company NOCACO (Kaduna), free from dust and contamination

Results

The various microstructures developed for different SiC additions are shown in Micrograph 1, Micrograph 2, Micrograph 3, Micrograph 4, Micrograph 5, Micrograph 6. The result of the density for different SiC addition is shown in Fig. 1. The results of the apparent porosity for different SiC addition are shown in Fig. 2. The effects of silicon carbide additions on the mechanical properties of Al–Si–Fe alloy are shown in Fig. 3, Fig. 4, Fig. 5, Fig. 6.

Discussion

Macrostructural studies revealed a reasonably

Conclusions

Considerable success was recorded in the synthesis of Al–Si–Fe alloy with silicon carbide addition using double stirring casting method. From the results obtained in this research, it can be concluded that addition of silicon carbide particles using this method to Al–Si–Fe alloy increases both the yield strength, ultimate tensile strength and hardness values up to a maximum values of 79.98, 106.12 N mm² and 67.0HRB, respectively, at 20% SiC addition. However, it is accompanied by a general

Acknowledgments

The authors acknowledge with thanks the management of the National Metallurgical Development Centre, Jos, Nigeria for allowing us used their equipments. We also like to acknowledge the support and encouragement given by Dr. S.A. Yaro during the production of the research materials.

References (13)

W. Zhou et al.
J. Mater. Process. Technol.
(1997)
T.W. Clyne
M.K. Surappa et al.
J. Mater. Sci.
(1981)
B. Maruyama
AMPTIAC Newsletter
(1998)
A. Jokinen, V. Rauta, 1992. Manufacturing and properties of aluminium alloy matrix composites, Final Report, Espoo:...
T.W. Clyne

There are more references available in the full text version of this article.

Cited by (118)

In-situ synthesized polymer-derived SiC reinforced aluminum matrix composites
2024, Journal of Alloys and Compounds
In the current work, in-situ formed polymer-derived SiC reinforced aluminum-based metal matrix composites were synthesized to uniformly distribute ceramic particles in metal matrix with good matrix-reinforcement interface. Polymeric precursor (allyl hydrido polycarbosilane) was cross-linked at 300 °C and the cross-linked precursor was mixed with molten aluminum at 800 °C under nitrogen using stir casting route to obtained composites reinforced with 2 wt%, 4 wt% and 7 wt% of SiC (particle size < 10 µm) distributed uniformly in the synthesized composites. Structural characterization of samples were performed using FTIR, XRD, optical microscopy, FESEM and Raman spectroscopy. The composites demonstrated significant improvements in hardness (∼58%), ultimate tensile strength (∼45%) and compressive strength (∼58%) for 7 wt% in-situ formed SiC in aluminum matrix compared to pure aluminum.
Effect of cooling rate on microstructure and properties of SiC<inf>P</inf>/A359 composites
2023, Materials and Design
The microstructure and properties of stirred cast SiCP/A359 composites under different cooling rates were studied. The strengthening mechanism of the composite material under three cooling rates was analyzed, and the failure mechanism of the composite material was elucidated by means of in-situ tension and EBSD testing. The results showed that increasing the cooling rate simultaneously refined the grains, secondary dendrites, and eutectic silicon, resulting in improved distribution uniformity of SiC and the stacking fault density of eutectic silicon. Additionally, the relationship between the secondary dendrite arm spacing (SDAS) and cooling rate (v) of the SiCP/A359 composite was described using the equation SDAS = 56.02v^(-0.3). There was a positive correlation between cooling rate and yield strength, with particle strengthening being the main contributor to the strength of composites with high cooling rates, resulting in significantly higher strength than samples with low cooling rates. The geometrically necessary dislocations (GND) density at the eutectic Si-Al boundary was found to be higher than other positions after the material was loaded, and the main crack propagated mainly along the eutectic region. Secondary cracks, including SiC cracking, eutectic silicon cracking, interface separation, and shrinkage cracking, may become part of the main crack by bridging.
Microstructure, texture, and mechanical properties analysis of novel AA7178/SiC nanocomposites
2023, Ceramics International
The current research aims to use stir casting to create a composite made from AA7178 aluminium alloy with nano SiC reinforcement at 1, 2, and 3 wt percent. Scanning electron microscope (SEM) with energy dispersive X-Ray (EDAX) was used to examine the microstructural changes of AA7178/nSiC composites. The addition of nano SiC reinforcement to the AA7178 matrix promotes grain refinement by providing additional nucleation sites for smaller grains to form. The microstructure of AA7178 composites underwent a considerable alteration due to the SiC addition, improving their mechanical properties. Electron backscatter diffraction (EBSD) study revealed the development of finer grains from coarser grains. All the samples seemed to have a completely random texture. The texture does not seem to be drastically altered by either the processing conditions or the incorporation of SiC. The uniform distribution of SiC particles and good interfacial bonding between the reinforcement matrix was confirmed by a transmission electron microscope (TEM). The maximum tensile strength was 206.12 MPa for AA7178 nanocomposite with 3 wt% of SiC reinforcement. The efficient transmission of load and dislocation strengthening were the strengthening mechanism for increasing in the tensile strength. The inclusion of 3 wt% of SiC particles increased the hardness of AA7178 nanocomposite to 51.70%.
Effect of ultrasonic treatment during stir casting on mechanical properties of AA6063-SiC composites
2023, Materials Chemistry and Physics
In this work AA6063-Silicon carbide composites were fabricated using conventional stir casting. Agglomeration of reinforcement particles which is a serious drawback in conventional stir casting was attempted to be reduced by applying ultrasonic waves to the composite melt after mechanical stirring. The composites were fabricated with different weight percentages (2,4,6 and 8%) of SiC particles having $10 μ m$ average particle size. The mechanical properties of the composites were evaluated for both the cases and were compared to study the influence of ultrasonic waves. It was found that the mechanical properties of the composite increased with increase in the weight percentage of the reinforcement up to 4 wt% SiC and reduced beyond that. The 4 wt% SiC stir cast composite subjected to ultrasonic waves showed 51.17%, 67.52% and 38.31% increase in ultimate tensile strength, yield strength and hardness respectively when compared to the base alloy.
Strengthening of Mg-Al-Zn-Mn alloy using SiC/Al nanocomposite extrusion
2022, Journal of Alloys and Compounds
Citation Excerpt :
This is due to the high surface energies and large surface-to-volume ratios of fine particles, leading to low wettability [15]. Further, in a study by Aigbodion and Hassan [16], it was found that addition of SiC greater than 25 wt% led to an agglomerated SiC phase in an Al–Si–Fe alloy. Therefore, when nanoparticles are added in the form of loose powders, segregated agglomerates form that either settle to the bottom of the crucible or float to the top of the melt, where they are afterwards removed as dross.
The use of lightweight alloys such as magnesium (Mg) is critical for achieving improved fuel efficiency and reduced emissions for automobiles, as well as increased range for electric vehicles. To promote their use in industry, in replacing iron-based alloys, their mechanical properties must be improved. This can be achieved through the addition of fine ceramic particles, producing metal matrix composites. One of the most promising alloys of Mg is Mg-Al-Zn-Mn alloy. The current work examined the influence of SiC nanoparticles on the microstructure and mechanical properties of Mg-Al-Zn-Mn alloy composites. The additives were prepared via the extrusion of aluminum powder combined with 60 nm SiC particles. The resultant grain refinement was indeed significant, with a 54 % reduction for the 0.02 wt% SiC addition level. In addition, a more uniform dispersion of the β-Mg₁₇Al₁₂ phase and fine spherical clusters of Mg₂Si were observed using scanning electron microscopy. The favorable morphology of the Mg₂Si intermetallics and the fine grain size resulted in an improvement in tensile strength of approximately 32 %. The enhancements in mechanical properties were attributed to the Hall-Petch mechanism. Thus, the SiC-containing composite materials may be effectively used for light-alloy strengthening, leading to increased use of Mg alloys in industry.
Investigation of mechanical and erosive behaviour of the Al 6061-SiC composites fabricated by stir casting
2022, Materials Today: Proceedings
Metal-matrix composites (MMC) are widely used in aerospace, defense and automotive industries due to their high specific strength, excellent wear resistance and significant strength to weight ratio. However, composites used in structural or engineering components goes through major erosive wear failure. Therefore, it is highly relevant to study the erosive wear behavior of the composites in compliance to their mechanical properties. In the current study, aluminum alloy composites are fabricated by employing silicon carbide (SiC) as a reinforcing agent. This composite sample was fabricated by using the application of the stir casting method in which the content of SiC particles was varied from 0, 4, 8 and 12 wt%. The effect of different particles concentration loading towards mechanical erosive wear behavior are then evaluated. The composites are subjected to mechanical tests including microhardness and impact strength tests. The result shows that the highest hardness and impact strength were attained at 150 Hv and 62 Joule respectively with composite fabricated with 12 wt% SiC content. Meanwhile the highest tensile strength were recorded at 400 MPa corresponding to composite that is loaded with 8 wt% SiC content. Erosion characteristics of the fabricated Al-SiC composites are analyzed by using Taguchi method and the significant control factors affecting the erosion rate of composites are identified through successful implementation of ANOVA. The result shows that the most significant factors in erosive wear of the composites are impact velocity and filler content.

View all citing articles on Scopus

View full text