Microstructural development in AlSiC composites made by resistance sintering of mechanically alloyed powders

Abstract

Abstract SiC particles were found to be distributed homogeneously in the aluminum matrix by the mechanical alloying (MA) process. It was observed that the aluminum matrix of the MA powders consists mainly of fine subgrains with a wide range of misorientations. In addition, a band structure consisting of lamellae of elongated subgrains was observed. The substructure of the aluminum matrix of MA powders indicates that the average temperature in the MA process in quite low, i.e. near room temperature. It was found that the fine substructure of MA powders can be maintained after resistance sintering. The high strength of the resistance-sintered AlSiC composites may be attributed to the fine subgrain structure in the aluminum matrix and the high dislocation densities which exist owing to the presence of a worked structure arising from the MA process, and are generated by the thermal mismatch between aluminum and SiC particulates.