Ultrasonic Effects on the Microstructures and Properties of the Cast Cu-0.2Be-1.0Co Alloy

The copper-beryllium alloys were usually processed by thermal treatments. Herein, inspired by promising ultrasonic effects, we investigate the microstructures and properties of the cast Cu-0.2Be-1.0Co alloy under different ultrasonic solidification conditions. It is found that, with intense ultrasonic treatments, the microhardness, micro-compressive performance and wear resistance exhibit significant improvements. The coarse α(Cu) dendrites in the cast alloy are greatly refined, fragmented and even converted into equiaxed grain structures without preferred crystal orientations. Moreover, the grain size greatly decreases from 1673.6 μm to 103.8 μm and dense dislocations occur. These microstructural transitions and resultant property enhancements can be attributed to acoustic cavitation, acoustic streaming and high-frequency vibration induced by ultrasonic field. The results in this work indicate that the ultrasonic effects can modulate the microstructures and improve the properties of the cast low-beryllium copper alloys effectively.