Investigation On Semisolid Microstructure Of AlSi3 Alloy And SiC_p/AlSi3 Composites By SIMA Processing

Particle reinforced metal matrix composites (MMCs), which are of many advantages such as better specific strength and specific modulus of elasticity, better wear resistance and corrosion resistance, and low thermal expansion coefficient, have broad application prospect in fields of aerospace, automobile and so on. For the forming of MMCs parts, up to now, there is not an ideal method which is suitable for casting ingots of MMCs serving as raw material, energy and material saving, mechanization, and volume production. So developing a new, energy saving method for MMCs parts forming near net shape has important significance. SIMA is a new semisolid process method, and has been applied more and more in recent years. But little report is found about processing particles reinforced MMCs parts with this method. The key of semisolid process is the preparation of semisolid slurry. This study serves AlSi3 alloy and SiCp/AlSi3 composites respectively as investigated objects, adopts SIMA semisolid process method, and investigates the microstructure evolution law of AlSi3 alloy and SiCp/AlSi3 composites in semisolid isothermal holding process, in order to providing theory guide for SIMA method semisolid forming of particles reinforced MMCs parts.First AlSi3 alloy was fabricated,and SiCp/AlSi3 composites was fabricated by mechanical stirring method.The microstructure evolution of AlSi3 alloy during semisolid isothermal experiment was studied. The effects of compression ratio and holding time on semisolid grain size,roundness,fractal dimension were analysed. The results show that as cast structure of AlSi3 alloy transfers from big and no directional dendrites...