Pseudoelastic Cycling and Two-Way Shape Memory Effect in β Cu–Zn–Al Alloys with γ-Precipitates

The effects of tensile pseudoelastic cycling of Cu-Zn-Al single crystals containing a dense distribution of small (≃10 nm) γ-phase precipitates have been studied. The σ-e curves show a reduction of hysteresis after the first transformation cycles caused by a shift of the direct transformation to progressively lower stresses. More prolongued cycling produces a tilting of the σ-e curves. Microscopic observations show the formation of dislocation bands in the β matrix, but in lower amounts in relation to precipitate-free specimens and after prolongued cycling