Grain size and pseudoelastic behaviour of a Cu–Al–Be alloy

Abstract

The effect of grain size on the pseudoelastic behaviour of a Cu-11.4 wt.% Al-0.5 wt.% Be shape memory alloy was studied. Annealing at 1073 K leads to grain growth with a kinetic exponent around 0.5. The martensite-start stress ( σ s), the pseudoelastic slope and the stress hysteresis decrease as the grain size increases. The effect of grain constraint on σ s for CuAlBe is stronger than for other shape memory alloys but it is very weak on the pseudoelastic behaviour. Pseudoelastic cycling with increasing strain beyond 2% leads to a decrease in σ s and an increase in the strain retained on unloading, due to increasing retention of the martensite phase on unloading. The important overheating needed for the transformation to β phase indicates that the stress-induced martensite is effectively stabilized.