Influence of in-situ TiB₂ particles on the microstructural, mechanical and abrasive wear behavior of A356 alloy

Abstract

Metal matrix composites (MMCs) have potential application in automobile and aerospace industries. The main challenges of these composites lie in the synthesis technique and many of the conventional routes fail to produce defect free MMCs. To overcome this drawback, a new synthesis technique called in-situ composites has recently been developed. In this present work, mixed salt reaction technique was used to synthesize Al-Si alloy (A356)/TiB₂ in-situ composites. XRD patterns of both as-cast composite and extracted TiBB2 particles did not reveal the presence of Al3Ti intermetallic phase. Microstructure of A356 alloys clearly showed the change from dendritic structure to an equiaxed structure with the addition of TiB2 particles. Both a-Al and eutectic Si size in A356 alloy are refined with TiB₂ additions. There was significant increase in tensile strength of A356 alloy without much sacrifice in ductility. The abrasive wear resistance of the A356 alloys was also improved significantly due to the addition of TiB₂ particles despite the fact that the TiB2 particle size is smaller than the SiC abrasive medium.