Effect of manganese and homogenization on the phase stability and properties of Cu–Al–Be shape memory alloys

Abstract

In this study, the effect of addition of manganese to the ternary Cu–Al–Be shape memory alloys on phase stability, phase transformation temperatures, microstructure, morphology and grain size has been investigated. Secondly, the effect of betatization temperatures and time period has been investigated on the phases and properties of Cu–Al–Be–Mn SMAs. Results reveal that the addition of manganese in the alloys with Al ≥ 11.8 wt.% forms coexistence of β1′ and γ1′ martensites, and manganese ≥1 wt.% forms austenite β1 (DO3). DSC studies exhibit two stage reverse transformation attributes to coexistence of martensites. Increase in manganese decreases the transformation temperatures and increase in betatization temperature and time increases transformation temperatures. Alloying manganese didn't exhibit significant grain refinement and results reduced shape recovery due to the coexistence of martensites.

Keywords

• Shape memory alloys
• Cu–Al–Be
• Manganese
• Thermal treatment
• Phase transformation
• Two stage transformation