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 byγ′(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. TheM _s temperature of the strengthened austenite was restored to nearly that of annealed austenite while the austenite was hardened toR _c 41 through precipitation and phase transformations. The observed austenite stabilization is attributed to the formation of G.P. zones or short-range order of less than ∼10? size. Formerly with University of California, Berkeley