A water-quenched martensitic CuAlNi shape-memory alloy was investigated by a combination of coincidence Doppler broadening and positron-lifetime spectroscopy, supported by positron-lifetime calculations. A high defect concentration was found in as-quenched samples. The positron-lifetime calculations suggested that the defects were not only single vacancies but also vacancies associated with dislocations and stacking faults. Annealing in the martensitic phase had no significant influence upon the vacancy concentration but resulted in a different chemical environment around the vacancies. After aging in the austenitic phase, the vacancy concentration decreased significantly.

Characterization of Defects in a Martensitic CuAlNi Shape-Memory Alloy. S.Van Petegem, D.Segers, V.Pelosin, J.Kuriplach: Applied Physics A, 2005, 81[5], 1039-44