Transformational elasticity in a polycrystalline Cu-Zn-Sn alloy

A study has been made of the transformational elasticity in a polycrystalline Cu-33.6 wt pct Zn-4 wt pct Sn alloy. The magnitude of the transformational elasticity was markedly dependent on the grain size/thickness ratio of the sample. Large reversible strains (<2.5 pct) were realized for samples in which the grains extend through the sample thickness. Samples with a smaller gs/t ratio exhibited very limited transformational elasticity. The gs/t ratio, considered to be a measure of the grain constraint, also affected the Ms, Mb, and AI temperatures. Although the stress-strain curves appeared quite reproducible after 4 loading-unloading cycles, some non-recoverable deformation was produced with each cycle. This permanent deformation was cumulative during extended cycling, giving rise to a decreasing amount of reversible strain. Increased cycling also reduced the load-unload hysteresis of the stress-strain curves.