Fabrication and characterization of squeeze cast AC4A Al/TiNi shape memory composites

摘要

Reinforcement of shape memory alloys within light weight metal matrix reveals compressive residual stresses in the matrices resulting in improved tensile properties of the composites. In the present study, Al/TiNi shape memory composites werefabricated by the squeeze casting technique. Optimal fabrication conditions for squeeze casting were obtained experimentally. Fairly good microstructure and matrix/reinforcement bonding observed in the squeeze cast Al/TiNi composites. Tensile tests of the composites were carried out above A{sub}f (austenite finishing temperature) which was found from DSC analysis. The amount of prestrain to induce the compressive residual stress in Al matrix and the recovery force of the TiNi were determined from tensilecurves of TiNi wire. Improved strength of the composite due to TiNi reinforcement as well as compressive residual stresses in Al matrix was identified. It was found that the total interfacial area between matrix and reinforcement which depends on the wire diameter also affected the strength enhancement.