The Twinning Microstructure and Damping Behavior in Mn30Cu (at%) Alloy

The twin boundary damping peak and the transformation damping peak constitute the temperature dependent damping behavior in Mn–Cu alloys. In order to observe the effects of twinning microstructure on the twin boundary damping behavior, a Mn–30 at%Cu alloy was finally treated by furnace cooling (FC) and aging after water-quenching (AG), respectively. Regular twin bands with the similar widths along some 101 twin boundary were observed in FC treated condition, while intersected twin bands with pointed fronts belonging to different 101 twin boundaries occurred in the AG treated specimens. Meanwhile, the twin boundary damping features were obtained based on dynamic mechanical analyzer (DMA) measurement, and increased activation energy and decreased peak damping capacity were found in the AG treated alloy. The distortion state of the interfaces enclosing the decomposed nanometer regions was considered to influence the twinning microstructure formation and hence alter the damping features of the twining microstructure.