The effect of dynamic aging on the cyclic stability of Cu₇₃Al₁₆Mn₁₁ shape memory alloy

This study focuses on the effect of dynamic aging on the thermo-mechanical cyclic stability of Cu₇₃Al₁₆Mn₁₁ (at%) shape memory alloy (SMA) during constant stress (isobaric) and stress-free heating-cooling experiments. Isobaric heating-cooling experiments under various tensile stress magnitudes revealed almost no residual strain up to 60 MPa. Subsequently, the cyclic stability of the samples was further investigated via thermal cycles under 60 MPa with increasing upper cycle temperature (UCT) values. The increase in UCT led to the ordering of the parent phase and formation of the bainite and α phases. In addition to the effect of UCT on the formation of bainite, stress had an accelerating effect on the bainitic transformation. The martensitic transformation temperatures increased due to ordering when UCTs were set to 120 °C and 145 °C and then started to decrease due to the formation of the bainite and α phases when the UCTs were set to 175 °C and 205 °C. Consequently, it was determined that the cyclic stability of Cu-Al-Mn SMAs for high temperature applications strongly depends on the UCT.