Simultaneously enhanced strength and elongation capacity in Cu-15Sn-0.3Ti alloy via regulation of IMCs

Due to the technical requirements of preparing Nb3Sn superconducting wires using the bronze method, the Cu-Sn-Ti alloy with high Sn content and matching mechanical properties with pure Nb as the substrate is the key to the smooth preparation of superconducting wires. However, the high content of Sn leads to the generation of a large number of intermetallic compounds (IMCs) in Cu-Sn-Ti alloy are the main reasons for the deterioration of the elongation and strength of Cu-Sn-Ti alloy. This work uses unidirectional solidification (US) and homogenization annealing (HA) methods to regulate the volume fraction and types of IMCs in Cu-15Sn-0.3Ti alloy. The volume fraction of IMCs decreases from 20.6 % to 0.1 % after HA, and the network delta phases (Cu41Sn11) transform to fine gamma phase (Cu3Sn) and CuSn3Ti5. The ultimate tensile strength (UTS) and elongation of the samples treated with HA increase by 2000 % and 94 %, respectively, and deformation twins are found in the stretched samples. The research results indicate that the elongation and UTS of Cu-15Sn-0.3Ti alloy are improved by the decrease of IMCs volume fraction and deformation twins formed during the tensile process.