Effect of powder oxidation on densification and properties of vacuum hot pressed Cu-Cr-Nb alloy

The densification behavior of oxidized Cu-8 at% Cr-4 at%Nb alloy powders by vacuum hot pressing and subsequent mechanical properties of alloy compares well with that of fresh powders with no oxides and hydrogen reduced powders sintered using same conditions. The reason for such observation is the presence of high vacuum and carbon atmosphere due to graphite die at the furnace temperature helping in the decomposition of oxide layer. Reduction of oxides of copper controls the overall densification process. A new mechanism for the densification of air-oxidized powders during vacuum hot pressing is also put forward. Present work indicates that reduction of powders is not needed if consolidated by vacuum hot pressing.