Evolution behavior of δ phase in Cu12Sn2Ni alloy and the corresponding effects on alloy property

Abstract

AbstractWith the increase of tin content in tin bronze, the rise of δ phase made the strength, hardness of tin bronze increase and the ductility decrease sharply, that difficult to process. In this paper, the Cu12Sn2Ni alloy was prepared by centrifugal casting, the microstructure and phase formation before and after heat treatment were observed by x‐ray diffraction, scanning electron microscope, and transmission electron microscope. The results showed that the as‐cast sample microstructure was composed of equiaxed grains rather than coarse dendrites. centrifugal casting inhibits tin diffusion to form metastable phase β′‐Cu13.7Sn. The as‐cast sample had good deformability and its tensile strength and elongation were 381.9 MPa and 12.4 %, respectively, which are higher than the mechanical properties of gravity casting. The tensile strength and elongation of the sample after furnace cooling at 620 °C/8 min are 439.5 MPa and 24.4 %, respectively, the increase was 16.6 % and 85.07 %, compared with the as‐cast samples, due to the solid solution strengthening, the second phase strengthening and the homogenization of the microstructure.