Effect of ball-milling time on structural characteristics and densification behavior of W-Cu composite powder produced from WO3-CuO powder mixtures

Abstract

Understanding the microstructure of W–Cu nanocomposite powder is essential for elucidating its sintering mechanism. In this study, the effect of milling time on the structural characteristics and densification behavior of W-Cu composite powders synthesized from WO3-CuO powder mixtures was investigated. The mixture of WO3 and CuO powders was ball-milled in a bead mill for 1h and 10h followed by reduction by heat-treating the mixture at 800°C in H2 atmosphere with a heating rate of 2°C/min to produce W-Cu composite powder. The microstructure analysis of the reduced powder obtained by milling for 1h revealed the formation of W–Cu powder consisting of W nanoparticle-attached Cu microparticles. However, Cu-coated W nanocomposite powder consisting of W nanoparticles coated with a Cu layer was formed when the mixture was milled for 10h. Cu-coated W nanopowder exhibited an excellent sinterability not only in the solid-phase sintering stage (SPS) but also in the liquid-phase sintering stage (LPS). A high relative sintered density of 96.0% was obtained at 1050°C with a full densification occurring on sintering the sample at 1100°C. The 1h-milled W-Cu powder exhibited a high sinterability only in the LPS stage to achieve a nearly full densification at 1200°C.