Micromechanical study of formation and evolution of martensite for Cu-Al-Ni single crystal by moire interferometry

The basic properties of pseudoelasticity of Cu-Al-Ni single crystal are stu died to analyze the morphology associated with the formation and evolution of martensite and the shape memory recovery process at different temperatur es. Use is made of a multifunctional macro-micro moire interferometry measu rement system. The beta(1) to beta(1)' phase changes are identified with th e stress-induced transformation of a Cu-13.7%Al-4.18%Ni (wt%) alloy. The in variant plane between the martensite and the parent phase is shown directly by fringe patterns. It is found that martensite appears in the shape of ba nds or thin plates on the surface of the specimen. The formation of martens ite is a very rapid process and martensite 'jumps' out until the specimen i s completely transformed into a single variant. The results reveal the mech anism and process of stress-type and temperature-induced martensitic transf ormation. (C) 2000 Elsevier Science Ltd. All rights reserved.