Effect of power ultrasound on microstructural characteristics and mechanical properties of Al81.3Sn12.3Cu6.4 monotectic alloy

The liquid phase separation process and solidification process of ternary Al81.3Sn12.3Cu6.4 monotectic alloy was accomplished with a 20 kHz ultrasonic field in the power range up to 500 W. As ultrasound power rised, the coarse primary (Al) dendrites turned into fine equiaxed grains, whose size decreased by one order of magnitude as that during static solidification. Meanwhile, rather than pronounced segregation of large secondary (Sn) blocks in the alloy sample solidified under static condition, tiny secondary (Sn) droplets dispersed homogenously within the (Al) matrix in the presence of ultrasound. Under the highest ultrasound power of 500 W, the spherical ternary (Al+Sn+θ(Al2Cu)) monotectic cells formed. The refinement of primary (Al) dendrites and uniform distribution of secondary (Sn) droplets induced by power ultrasound result in the improvement of microhardness, wear resistance, compressive and yield strength of ternary Al81.3Sn12.3Cu6.4 monotectic alloy.