The effect of processing conditions and subsequent heat treatment on the transformation behavior of some rapidly solidified copper-base shape memory alloys

Abstract

A number of copper-base alloys (Cu-Al, Cu-Al-Ni) have been processed by chill block melt spinning and planar flow casting. A range of processing conditions was employed to observe how these affected the subsequent transformation behavior of these alloys. Characteristic transformation temperatures were analyzed in a differential scanning calorimeter and structures examined by both scanning and transmission electron microscopy. The high transformation temperatures of Cu-Al alloys made them unsuitable for monitoring the effect of process conditions. Cu-Al-Ni alloys withM s temperatures around room temperature are sensitive to both wheel material and provision of secondary quenching facilities. Some alloys containing titanium did not exhibit a shape memory phenomenon after rapid quenching. Heat treatment of alloys in the β and β1 phase fields was undertaken. β phase annealing resulted in grain growth and an increase inM s , while in the β1 phase, stabilization of transformation temperatures could be obtained below 300 °C. The effect of low stresses was also monitored in a thermo-mechanical analyzer (TMA).