Densification and microstructure of the PlMed W-15wt% Cu nanocomposite powder

Abstract

The densification process and related microstructure evolution during sintering of the powder injection molded (PlMed) W-15wt% Cu nanocomposite powder have been investigated. The densification process of the PlMed composite powder was analyzed in terms of dilatometry, shrinkage anisotropy and microstructure. Especially, the sintering behavior of the W-Cu composite powder compact was in-situ analyzed during heat up, which might be closely related to gas evolution in the early stage of sintering. It was found that residual carbon reduces oxides, that hydrogen is unable to reduce, forming Co gas at 700 approx. 1000°C. Such carbon effect resulted in enhancement of the solid state sintering as well as formation of inhomogeneous microstructure of the PlMed W-Cu nanocomposite powder. Based on the measurement of gas evolution, the most effective removal of residual impurities and the best consolidation were achieved without promoting solid state sintering.