Enhanced strength-ductility synergy in CuSn alloy via tuning Ti content

Abstract

CuSn alloy is the key raw material for the preparation of Nb3Sn superconducting wires. The properties of Nb3Sn wires can be greatly enhanced by preparing CuSn alloys with high solid solubility of Sn atoms and adding Ti elements. In this paper, the CuSn alloy was prepared by directional solidification with Ti added. Then the homogenization system is determined by calculation and it is expected to improve the structure segregation and mechanical properties of the alloy. Therefore studies the distribution of Ti elements and the relationship between the microstructure evolution and mechanical properties in CuSn alloy. The results indicate that the as-cast structure of the alloy is mainly a core-shell structure, and the grains show a good (001) orientation. It was also found that the Sn-rich phase in the alloy transforms to α-Cu solid solution during homogenization. The mechanical property tests show that the CuSn alloy with 0.3 wt% Ti content has both high strength (409 MPa) and elongation (69%). The main mechanism for enhanced the strength-ductility of the alloy is as follows. The core-shell structure allows sufficient diffusion of Sn atoms during the homogenization treatment, and the CuSn3Ti5 phase hinders the twin growth. As a result, the ductility of the alloy increases significantly. When the Ti content continues to increase until the CuSn3Ti5 phase segregates, causing the alloy's strength and elongation to plummet.