Thermoelastic martensite and shape memory effect in B2 Base Ni-Al-Fe alloy with enhanced ductility

A ductile shape memory alloy of the Ni-AI-Fe system has been developed using principles through the control of microstructure. Addition of Fe to the binary Ni-Al shape memory alloy allows the introduction of a ductile face-centered cubic (fcc) phase in an otherwise extremely brittle β phase alloy, leading to an improvement in its ductility while retaining its ability to exhibit shape memory arising from the martensitic transformation of theβ phase to Ll₀ structure. It is shown that the transformation temperature in the ternary Ni-AI-Fe alloy can be easily controlled by the preannealing in the β+ γ region. Experimental results on the effect of different annealing treatments on the microstructures and the shape memory behavior in this alloy are presented and discussed.