Fabrication and mechanical properties of bulk NiTip/Al composites prepared by friction stir processing

Friction stir processing (FSP) was used to prepare NiTip reinforced 6061Al bulk composites with the aim to avoid deleterious Al-NiTi interface reaction occurred in cast and powder metallurgy processes. NiTip were homogeneously distributed in the Al matrix without interfacial reaction. The intrinsic characteristic of a reversible thermoelastic phase transformation of the NiTip was observed in the composites. The as-FSP composites showed lower tensile strengths and higher elongation than the as-received 6061Al-T651, and the strengths increased greatly after both aging and T6 heat treatments without interfacial products being detected. The results show that FSP is an effective way to produce NiTip/Al composites with good shape memory effect and mechanical properties.