A FUNDAMENTAL-STUDY OF THE CHI-PHASE PRECIPITATION IN CU-AL-NI-TI-(MN) SHAPE-MEMORY ALLOYS

chi-phase particles are precipitated when Ti is added as grain refiner to Cu-Al-Ni shape memory alloys. The size distribution of these preci pitates is a function of the thermomechanical history of the alloy. Th e further addition of Mn to improve the alloy properties causes the ap pearance of a new set of small chi-phase precipitates. The conditions for their appearance are described together with a qualitative model w hich explains their stability. The presence of Mn is shown to play a c entral role in controlling the growth of the chi-phase precipitates. C opyright (C) 1996 Acta Metallurgica Inc.