The effect of superelastic strain on the damping capacity in columnar grained Cu Al Mn shape memory alloy
Abstract Columnar grained Cu Al Mn shape memory alloy (SMA) can experience high superelastic strain exceeding 7% and exhibits a nearly 100% superelastic recovery ratio due to its straight grain boundaries and strong texture along the solidification direction, which allows it to reach the strain level of a single crystalline Cu based or Ni Ti SMAs and possesses a potential for damping applications. In this paper, the damping capacity of Cu Al Mn SMA in various deformation conditions during a strain controlled superelastic cyclic tensile process was studied. The anisotropy characteristics and the cyclic effect of damping capacity were analysed. The damping capacity of columnar grained Cu Al Mn SMA increases as the loading strain increases in superelastic tensile processes, and a large damping capacity anisotropy occurs. At low loading strain 6% T 0deg and T 15deg samples can achieve a good damping capacity because of high superelasticity and plasticity. In addition, the damping capacity of columnar grained Cu Al Mn SMA along the solidification direction has a significant cyclic effect. At the same loading strain (4% 10% DW1% and loss angle, DW/2pW first decrease to the minimum, then increase to the maximum and, finally, decreases as the number of cycles increases. The minima and maxima of DW1% and DW/2pW at different strain amplitudes correspond to the similar residual strain ratio, er/et. The change curves of damping capacity related to er/et can be divided into three stages: the stable damping capacity stage with low residual strain; the rapidly increasing damping capacity stage; the sharp cumulative stage of residual martensite with limited values of strain damping capacity.
Journal of Alloys and Compounds