Phase transformation and stabilization of a high strength austenite

An investigation of the phase transformation and the austenite stabilization in a high strength austenite has been made. An Fe-29Ni-4.3Ti austenite age-hardened by gamma-prime (Ni3Ti) precipitates showed a further increase of strength after martensitic and reverse martensitic phase transformations. The stability of ausaged austenite as well as ausaged and transformation-strengthened austenite was improved significantly through an isothermal treatment at 500 C. The Ms temperature of the strengthened austenite was restored to nearly that of annealed austenite while the austenite was hardened to R(C) 41 through precipitation and phase transformations. The observed austenite stabilization is attributed to the formation of GP zones or short-range order of less than about 10A in size.