Abstract:The microstructure, martensitic transformation behavior, mechanical properties and shape memory effect of Ni₅₄Mn₂₅Ga₁₅Al₆ high-temperature shape memory alloy were investigated. By comparing with the Ni₅₄Mn₂₅Ga₂₁ alloy, the effect of Al addition on the properties of Ni-Mn-Ga alloys was analyzed. The results show that the Ni₅₄Mn₂₅Ga₁₅Al₆ alloy has a single-phase tetragonal non-modulated martensite structure with lamellar twins_. The martensitic transformation start temperature of this alloy is up to 190 °C, displaying the promising application as a high-temperature shape memory alloy. Al addition in Ni-Mn-Ga alloy can decrease the martensitic transformation temperatures due to the effect of size factor and improve the strength and plasticity. However, the shape memory effect is reduced remarkably with the Al addition.

Key words: shape memory alloy; Ni-Mn-Ga; Al addition; martensitic transformation