Enhanced stress relaxation resistance and strength-electrical conductivity combination of graphene reinforced Cu-0.5La composite wire for high temperature applications

Abstract

The temperature-rise effect caused by the boom of high-power equipment for communications and transportation brings new challenges to the stress relaxation resistance and tensile properties of Cu wires at elevated temperatures. In order to meet higher property requirements, herein we introduced a graphene reinforced Cu-0.5La alloy (Gr/Cu-0.5La) composite wire prepared by in-situ synthesis and powder metallurgy methods. Thanks to the distribution of in-situ formed graphene and Gr-La₂O₃ hybrid reinforcements at the grain boundaries, the mechanical properties of the composite wire were improved. The uniformly dispersed graphene at grain boundaries created a strong pinning force, which limited the mobility of the grain boundaries and ultimately improved their thermal stability. Notably, the composite wire exhibits significantly enhanced stress relaxation resistivity, demonstrating advantages over element doping strategy. Meanwhile, the electrical conductivity of the Gr/Cu-0.5La composite wire reaches 89.3 % IACS, accompanied by a reduced temperature coefficient of resistance. Cyclic stress relaxation tests revealed that the excellent high-temperature mechanical properties mainly come from the dislocation-controlled strengthening and deformation mechanisms. The excellent comprehensive performance achieved proposes the good application prospects of Gr/Cu-0.5La composite wire in a wide temperature range.