The effect of CuO powder on the pore elimination during the liquid phase sintering of Fe-Cu alloys has been investigated. Part of Cu in the powder mixture has been replaced by CuO powder while keeping the total Cu content at a constant value. The powder compacts have been sintered at 1200℃ under $H_2$ atmosphere.
With increasing CuO fraction, pore elimination is slower and the limit of densification appears. This effect is attributed to the evolution of $H_2O$ gas by reduction of CuO, which is expected to build up pressure in the isolated pores. The presence of gas in the isolated pores is confirmed by resintering the sintered specimen in a liquid bath of the matrix composition.
These results show that the densification during liquid phase sintering can be significantly retarded by the gas produced by reduction of metal oxides.
