Time-dependent phenomena during martensite ageing of Cu-Al-Be shape memory alloy

Abstract

Martensite ageing effects have been studied in the β 1 ' martensitic phase of a Cu-10.5wt%Al-0.5wt%Be alloy, exhibiting pronounced stabilization of martensite, by means of calorimetric studies and acoustic measurements. The latter were performed in the range of non-linear anelasticity for temperatures between 300 and 9 K and allowed one to investigate variations of the mobility of linear/planar defects of martensite (partial dislocations, intervariant boundaries) for different heat treatments and ageing times in the martensitic state. The conclusion is drawn that martensite ageing includes homogeneous and heterogeneous components. The former occurs in the bulk of a sample, whereas the latter is localized in the vicinity of lattice defects such as intervariant boundaries and/or partial dislocations limiting stacking faults.