Effects of Cu51Zr14 inoculant and caliber rolling on microstructures and comprehensive properties of a Cu–Al–Mn shape memory alloy

Abstract

Grains of a Cu–Al–Mn shape memory alloy (SMA) were significantly refined by combined use of Cu51Zr14 inoculant and caliber rolling, and the effects of grain refinement on microstructures and comprehensive properties were also investigated. It is found that along rolling direction (RD) and normal direction (ND) the Cu–Al–Mn SMAs present fibrous and recrystallized equiaxed grains, respectively. Damping tests show that with the decrease of average grain size, the internal friction (IF) background of the Cu–Al–Mn SMAs increases remarkably due to the increased densities of various interfaces. The most noteworthy feature is that the inoculant refined Cu–Al–Mn SMA with 60% rolling reduction possesses abnormally high IF peak caused by twins. It is believed that the growth and aggregation of γ2 particles along martensite interfaces should be responsible for this. Because in this way the pinning effect of these particles on twins is efficiently weakened. Tensile mechanical properties can also be dramatically improved by grain refinement. This has been ascribed to the principle of fine grain strengthening, the decreased mobility of martensite variants, the increased difficulty of grain coordination deformation as well as the elimination of casting defects.