Enhancement of the microstructure homogeneity and mechanical performance of the As-Cast Mg/Mg2Si in-situ composite through friction stir processing

Abstract

Multipass friction stir processing (FSP) with 100% overlap was applied to in situ Mg/Mg2Si composite in an effort to modify its as-cast microstructure. The results indicated that FSP eliminates porosities, breaks up the massive high aspect ratio Mg2Si particles and refines and homogenizes the microstructure. Uniform microhardness was observed in the FSP stir zone of the composite which was not the case for the as-cast material. As compared to the as-cast specimen, the results of the tensile test revealed the simultaneous increase in ductility by 4.5 times and in strength by 2 times by performing one pass of FSP. Investigating the fracture surface of FSP samples showed a high density of cracked primary Mg2Si particles which shows that load transfer to reinforcing particles has occurred due to the high strength of their interface.