Effects of macroscopic defects on the damping behavior of CuAlMn shape memory alloy

Two types of macroscopic defects, graphite particulates and pores with millimeter dimensions, were introduced into the Cu-11.9Al-2.5Mn (wt.%) shape memory alloy, and the damping behaviors of the resultant composites were investigated. It is found that the damping capacity of the porous and the composite was greatly elevated particularly at relatively low temperatures. The higher the volume fraction or the smaller the size of the macroscopic defects, the higher the damping capacity of the composites. However, the graphite particulates showed more significant damping enhancement than the pores because of the combined effects of the matrix, dislocations and the particulates themselves.