Production and Properties of Ni-Al-Based High Temperature

NiAl based shape memory alloys have good combination of high temperature shape memory effect, high temperature oxidation and corrosion resistance despite the room temperature brittleness. In the present study of the effect of chemical composition and heat treatment variables on the mechanical properties, shape memory effect and magnetic behavior of four different NiAl-based alloys were examined. After hot rolling, annealing and solution treatment samples were subjected to tensile test, hardness test, DSC analysis, shape memory effect measurement and magnetic properties. Samples were aged at 400 ºC and some at 600 ºC to study the effect of aging temperature on mechanical properties and shape memory behavior. The NiAlCo alloy-2 showed better mechanical and magnetic properties and higher transformation temperature as compared to NiAlFe alloy-1. The shape memory effect of alloy-1 is better (12% more) than the alloy-2. It has been also found that addition of cobalt in NiAlFe alloy (alloy-3) increases the martensitic transformation temperature up to 524 ºC with out any significant increase in shape memory effect.