Study of γ2 precipitation in Cu–Al–Be shape memory alloys

Abstract

Thermal aging between 250 and 500 °C of ordered β phase in a polycrystalline Cu–Al–Be shape memory alloy were performed, and the formation of phase γ₂ was studied with optical and transmission electron microscopies and XRD techniques. The growth of γ₂ phase shows a polynomial behavior, and Avrami curves as well as a Time–Temperature–Transformation diagram were constructed from these results. In addition, the formation of stable γ₂ precipitates was studied in aged Cu–Al–Be ribbons. The presence of α regions surrounding γ₂ precipitates for longer aging times at higher temperatures was observed, giving a consistent precipitation scheme.