The microstructure, martensitic transformation, and thermal cycling stability of Ni56Mn21Cu4Ga19 high-tem- perature shape memory ribbons subjected to different annealing conditions were investigated and compared with that of the bulk master alloy. It was shown that 7 phases precipitated in the bulk and the ribbons annealed for 5 h at 800 and 900 ℃, which lead to the same poor thermal cycling stability. However, the formation of 7 phase was inhibited in the ribbons annealed at 700 ℃ for 30 rnin and 5 h, which remarkably improved the thermal cycling stability and also shifted the martensitic transformation to a lower temperature with a drop of about 60 ℃ than other three samples.
Xi-Li LuDe-Xi SuFeng ChenWei-Li LiuYang-Guang ShiYun-Xiang TongLi Li
