Modification of Al-Si Alloy by Non-Conventional Route

Al-Si hypereutectic alloys find application in small engines, pistons for air conditioning compressors and other components in automatic transmission. They are lightweight and have an outstanding wear resistance, a lower thermal expansion coefficient, and very good casting characteristics. Use of such alloys gets limited because of the presence of extremely hard primary silicon phase which reduces its machinability. The present work makes an attempt to improve upon the mechanical properties of Al-17Si hypereutectic alloys by modification of primary silicon and eutectic silicon through non conventional route. The alloys are modified using oxides and chlorides addition. The effect of oxides and chlorides on the morphology and size of Si phases in the hypereutectic Al-Si alloys are investigated. The mechanical properties like hardness, tensile strength and % elongation were observed to increase in modified alloys. The improved properties are dependent on uniform distribution of fine fibrous eutectic Al¿silicon and fine primary Si- particles. The results of the work should be useful for academic researchers and others interested in useful information about Al-Si alloys.