الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 94 |  |  |
| | | from | 94 | | |
Abstract
Aluminum based metal matrix composites (MMCs) have been extensively studied in the last two decades. These composites exhibit attractive physical and mechanical properties, such as high specific modulus, good strength, long fatigue life, superior wear resistance, and improved thermal stability. Such properties allow these composites to have numerous applications in the aerospace, automobile, electrical, desalination, and military industries. In the present study, A356 aluminum alloy metal matrix composite (MMCs) reinforced with various volume fractions (5, 7.5, and 10 Vol. %) of silicon carbide particles (SiCp) are fabricated by stir casting at various stirring speeds 300, 600, and 900 rpm for 10 minutes at 720oC. The effect of SiCp content on density, porosity, hardness, modulus of elasticity, 0.2% offset compression proof stress, maximum compressive stress, wear resistance, strain hardening rate at low strains, and microstructure of all samples are investigated. It is observed that, increasing the stirring speed to 900 rpm, enhances homogeneity of SiCp distribution in the A356 matrix alloy. Density measurements show that the samples contain low porosity, which increases with increasing volume fraction of SiCp. The hardness, 0.2% offset compression proof stress, and compressive stress at maximum strain increase with increasing volume fraction of SiCp. At 10Vol.% SiCp, Vickers Hardness Number is 16% greater than that of the matrix alloy. Moreover, at 5 Vol.% SiCp, the modulus of elasticity is 18% greater than that of the matrix alloy. Besides, at 10Vol. % SiCp, 0.2% offset compression proof stress is 63% greater than that of the matrix alloy, and compressive stress at maximum strain achieved for present composites is about 40% greater than that of iii the matrix alloy. The strain hardening rate increases progressively with the increase of the hard SiCp content. However, such increase becomes much slower at values of SiCp contents higher than 7.5%. In general, the rate of strain hardening decreases with the increase of applied strain. Furthermore, the results of wear test show that, the wear resistance of MMCs increases with increasing volume fraction of SiCp.