Study on the regulation of microstructure and mechanical properties of Cu–15Sn-0.3Ti alloy by a novel mechanical-heat-electricity synergistic method

Abstract

The matching of mechanical properties between Cu–15Sn-0.3Ti alloy and Nb was the key to the formation of Nb3Sn superconducting wires. However, the Cu–15Sn-0.3Ti alloy treated with homogenized annealed (HA) still could not meet the requirements for synergistic deformation with Nb. In this work, a novel mechanical-heat-electricity synergistic method was proposed, which successfully formed equiaxed crystal microstructures with annealing twins (ATs) to enhance the strength of Cu–15Sn-0.3Ti alloy without loss of elongation. The experimental results indicated that the combination method of Rotary swaging (RS) and Electric pulse treatment (EPT) could induce recrystallization of deformed microstructure to refine the average grain size of the HA state sample from≥500 μm to 9.3 μm, and the UTS and YS were increased by 34 % and 28 %, respectively. It is worth noting that this process was completed in only 90 s. The relationship between the changes in mechanical properties of Cu–15Sn-0.3Ti alloy and microstructure evolution during the EPT process was elucidated. The role of stacking faults (SFs) in the formation of ATs and recrystallization was revealed. The recrystallization efficiency of EPT and annealing treatment was compared by calculation.