Bulk NiTip/Al composites prepared by friction stir processing

Abstract

Friction stir processing (FSP) was used to prepare shape memory alloy particles (NiTip) reinforced 6061Al bulk composites with the aim to avoid deleterious. Al-NiTi interface reaction that occurred in cast and powder metallurgy processes. NiTip were homogeneously distributed in the Al matrix without interfacial reaction. Conventional T6-treatment (solution + aging) showed little effect on the interfacial microstructure. The NiTip in both the as-FSP and T6-treated composites still maintain the intrinsic characteristic of a reversible thermoelastic phase transformation. The shape memory characteristic of the NiTip decreases the CTE of the Al matrix, and an apparent two-way shape memory effect is observed in the cold-rolled composite. The composite owns a good combination of damping and mechanical properties.