Quenching effects in Cu–Al–Mn shape memory alloy

In this paper the effect of quenching from different temperatures (Tq) in a Cu–Al–Mn alloy is studied. This alloy system, which displays an L21 ordered structure, transforms martensitically at an intermediate temperature TM, and undergoes a spin freezing process at a lower temperature Tf. Positron annihilation measurements have shown that after the quench, an excess of vacancies is retained in the system, depending on Tq. In addition, both TM and Tf have been found to be sensitive to Tq. This has been attributed to frozen-in disorder induced by the quench. Experimental results have been interpreted in terms of the growth of magnetic clusters, quenched-in vacancies and atomic disorder.