Obtaining superior damping property of a Cu–Al–Mn shape memory alloy through ultra-high temperature aging

Abstract

Ultra-high temperature aging was conducted on the Cu-11.9Al-2.5Mn (wt.%) shape memory alloy (SMA) with the aim of damping improvement. The martensite laths were refined, and the controllable precipitation of γ2 phase was realized. As the aging temperature decreased or the aging time prolonged, the amount of γ2 particles increased. The damping of the Cu–Al–Mn SMA measured in this study belongs to non-linear damping, and the damping plateau in the martensite state mainly arises from the sliding of the martensite/martensite interfaces and the stacking faults in martensitic variants. The increased density of the martensite/martensite interfaces caused by grain refinement, the de-pinning of dislocations, and the annihilation of quenched-in vacancies after aging contributed to the increase of damping, whereas the increased density of stacking faults and the pining of γ2 particles on various interfaces leaded to the decrease of damping. The specimen aged at 590 °C for 5 min has the highest damping plateau. Its damping capacity at room temperature is 3.5 times that of the quenched specimen. The effect of aging on the tensile properties was also studied, and based on in-depth microstructural observation, correlated mechanisms were discussed.