Quenching effects in Cu-Al-Mn shape memory alloy

In this paper the effect of quenching from different temperatures (T-q) in a Cu-Al-Mn alloy is studied. This alloy system, which displays an L2(1) ord ered structure, transforms martensitically at an intermediate temperature T -M, and undergoes a spin freezing process at a lower temperature T-f. Posit ron annihilation measurements have shown that after the quench, an excess o f vacancies is retained in the system, depending on T-q. In addition, both T-M and T-f have been found to be sensitive to T-q. This has been attribute d to frozen-in disorder induced by the quench. Experimental results have be en interpreted in terms of the growth of magnetic clusters, quenched-in vac ancies and atomic disorder. (C) 1999 Elsevier Science S.A. All rights reser ved.