Microstructure, martensitic transformation and shape memory effect of Ni38Co12Mn41In9 alloy

• Ni38Co12Mn41In9 alloy exhibited two-phase microstructure of martensite and γ phase.
• The martensite and austenite transformation starting temperatures were 65 °C and 122 °C.
• Perfect shape memory effects were obtained although alloy had a mass of γ phase.
• A 0.8% of two-way shape memory effect was observed after thermomechanical process.

In this study, the microstructure, martensitic transformation and shape memory effect of Ni38Co12Mn41In9 alloy were investigated. It was found that Ni38Co12Mn41In9 alloy exhibited a two-phase microstructure consisting of martensite and γ phase. The martensitic and austenitic transformation temperatures were 65 °C and 122 °C. Results showed that, although Ni38Co12Mn41In9 alloy had a mass of γ phase, almost perfect shape memory effects could be obtained resulting from a small grain size and circularly shaped of γ phase. The largest shape memory effect increased to 5.4% with 100% of shape recovery rate during the second thermomechanical process. Meanwhile, a 0.8% of two-way shape memory effect was observed due to the growth of favorably oriented martensite variants during thermomechanical process.