MARTENSITIC-TRANSFORMATION OF A CUZNAL-SHAPE MEMORY ALLOY STRENGTHENED BY HOT-ROLLING

Lattice defects were introduced into stable austenite (beta) of a CuZn 27Al 4 alloy by a hot-rolling and quenching process (ausforming, AF). The amount of deformation was varied between zero and 1.54, the AF tem peratures T(AF) between 800 and 650 degrees C. At T(AF) < 700 degrees C the alloy forms a mixture of (alpha + beta) phase and is rendered un transformable, while the other ausforming treatments do not reduce tra nsformability. They lower the temperature range of martensitic transfo rmation cycles and improve considerably the conventional strength prop erties. The interpretation of these results is based on the microstruc ture, especially the defect structure in austenite. (C) 1998 Elsevier Science S.A. All rights reserved.