Hot Compression Deformation Behaviors and Microstructure Evolution for Brittle Au-20Sn Eutectic Alloy

Abstract

The hot compression test of Au-20Sn alloys with different solidification structures was carried out. The deformation behaviors and microstructure evolutions during hot compression were investigated. The results indicate that the fine fully lamellar eutectic structure without primary phase exhibited a very low yielding stress and a low stress platform, while the coarse lamellar with large primary Au5Sn phase showed rather high in that value. After compression, the lamellar eutectic tended to be equiaxed due to dynamic recrystallization, the large primary phase became separate dendrites or split into small dendrites, and the small roselike primary phase partly dissolved in the eutectic matrix. The rate of recrystallization also increased as the primary phase eliminated and lamellae was refined. It is suggested that refining eutectic lamellae and eliminating the primary Au5Sn phase in the as-cast microstructure by solidification optimization are an effective way to improve the workability greatly for brittle Au-20Sn eutectic alloy.