Study on the microstructure and properties of WCu alloy foils prepared by cyclic warm rolling

Abstract

The initial production of a W30Cu foil with a thickness of 0.1 mm and high relative density (99.9 %), as well as excellent physical and mechanical properties, was achieved through the utilisation of hot-press sintering (HPS) in conjunction with cyclic warm rolling. The impact of rolling deformation on the microstructure and overall performance of the composite material was examined, and the coordinated deformation mechanisms occurring during the rolling process were investigated. As the reduction rate increased, the deformation mechanism of the W30Cu composite material shifted from a Cu-phase-dominated plastic deformation to a cooperative deformation involving both the Cu and W phases. The number of high-angle grain boundaries (HAGBs) increased gradually with the occurrence of dynamic recrystallisation, accompanied by an expansion in the thickness of the W/Cu interface diffusion layer. The yield strength and tensile strength exhibited a gradual increase during the cyclic warm rolling process, while the coefficient of thermal expansion (CTE), electrical conductivity (EC) and thermal conductivity (TC) demonstrated a gradual decrease. Upon reaching an accumulated reduction rate of R98% (0.1 mm), the yield strength of the W30Cu composite material reached 767 MPa, the tensile strength reached 887 MPa, and the CTE, EC and TC were 210 W/(m·K), 40.8 % IACS and 6.2 × 10⁻⁶/K, respectively.