Aging behavior in Cu-Al-Be shape memory alloy

This article reports positron annihilation spectroscopy and calorimetric me asurements of the aging behavior in a Cu-Al-Be shape memory alloy. An exces s of single vacancies is retained in the alloy as a result of a quench. All vacancies in excess disappear after long aging time, and a migration energ y E-M = 1.0 +/- 0.1 eV for this process has been found to be larger than in other Cu-based shape memory alloys. The good correlation found for the con centration of vacancies and the shift in the martensitic transition tempera ture demonstrates that, in Cu-Al-Be, changes in the transition after a quen ch are deeply related to the excess of vacancies. (C) 1999 American Institu te of Physics. [S0021-8979(99)02101- 5].