A Study of Martensite Formation in Powder Metallurgy Fe-Mn-Si-Cr-Ni Shape Memory Alloys

Abstract

Abstract Parallelepiped specimens were pressed and sintered from as-blended powders of shape memory alloy (SMA) with nominal chemical composition 66Fe-14Mn-6Si-9Cr-5Ni (mass %). Specimens were hot rolled, spark erosion cut for tensile tests, solution treated and pre-strained up to 6%. XRD analyses determined the presence of both stress-induced ɛ (hexagonal close packed) and α’ (body center cubic) martensites in a γ (face center cubic) austenite matrix. In the specimens heat treated at 1273 and 1373 K, as an effect of PM processing, large amounts of α’were initially formed but this phase became unstable during pre-straining..