Enhanced Property of W–Cu Composites by Minor Addition of Ag

Abstract

Nano-scale W–20Cu (mass%) and W–18Cu–2Ag (mass%) composite powders were obtained by mechano-thermochemical process, followed by liquid phase sintering process from 1200 to 1300°C. The results indicate that the relative density and electrical conductivity of W–18Cu–2Ag composite were much superior to the W–20Cu composite at all temperatures. Microstructural investigation reveals that minor addition of Ag is beneficial to the densification of W–Cu composite. This can be ascribed to the stronger the wettability and capillary force of liquid Cu–Ag to W compared to that of pure Cu. Furthermore, during cooling Ag can precipitate into the voids between the W particles in W-rich area where is hard to be infiltrated by liquid Cu at high temperature, which is also beneficial to electrical conductivity.

Schematic representation of the densification process of W–Cu and W-18Cu–2Ag composites during sintering and subsequent cooling process.