Alloy Design and Solidification Microstructure Analysis of Equiatomic CuSnZn and CuSnAl Alloys

The alloy design of the equiatomic CuSnZn and CuSnAl alloys for the development of the Medium Entropy (ME) bronzes was performed by the empirical alloy parameters. The solidification microstructures of the metallic mold casting ingots in the equiatomic CuSnZn and CuSnAl alloys were investigated by X-ray diffraction, optical and electron microscopy. The repulsive tendency between Sn and other constituent elements was observed in the ingots of equiatomic CuSnZn and CuSnAl alloys, resulting in the Sn-rich liquid formation via the liquid phase separation in the equatomic CuSnAl alloys and the enrichment of Sn element at the inter-dendrite regions of the equiaxis dendrite structure in the equiatomic CuSnZn alloys. The significant segregation tendency of Sn element indicates the difficulty in the development of the equiatomic Cu-Sn-based ME bronzes with a single solid solution phase.