STUDY OF THE QUENCHED STRUCTURE AND OF THE TRANSFORMATION SEQUENCES DURING A SLOW HEATING OF SHAPE-MEMORY CU-AL-NI ALLOYS

Quenching of Cu - Al - Ni shape memory alloys of near-eutectoidal comp osition shows that the martensite structure evolves gradually from bet a' to beta'(1) type when the Al content varies between 12.8 and 13.3 w t. %. Besides, it has been noticed that a nickel addition (< 4.3 wt. % ) modifies simultaneously the composition of the eutectoid point and t he domains of different martensitic structures. During a slow heating of the quenched structure, the transformation sequences of the martens ite into the parent phase (beta(1)), then the decomposition of this ph ase into the equilibrium (alpha + gamma(2)) phases, and finally, the r edissolution of all phases to form the beta phase at high temperature, are shown to exist for all alloys.