In this study, slight amount of nio

In this study, slight amount of niobium (0.1 and 0.5 wt%) was added into Fe-30Mn-6Si-5Cr alloy. The martensitic transformation, microstructures, and shape memory performance resulting from treatments of aging and shape memory training are analyzed. The slight Nb addition in Fe-30Mn-6Si-5Cr alloys can exhibit several effects of solid-solution strengthening, grain refining, increasing stacking fault probability and promoting the nucleation and growth rate of aging precipitates, which all contribute to the improvement of alloy’s shape memory performance. The shape recovery ratio increases in the early cycles of shape memory training, ascribing to the formation of preferentially orientated stress-induced ε martensites and the incompletely reverted ε martensites after recovery heating. After a critical training cycle, the shape recovery ratio begins to decline due to the hindrance of the mobility of partial dislocations and hence the formation of stress-induced ε martensites and their reverse transformation. The presence of α' martensites also result in imperfect reverse transformation and limit the shape memory performance.