The role of alloying elements on the sintering of Cu

The influence of alloying elements on the sintering behaviors of Cu is investigated by using Cu green samples doped with 0.5 wt% of Cr, Ti, Al, Mo, Nb and W. The sintering of Cu is greatly promoted by adding Cr, Ti and Al, but impeded by adding Mo, Nb and W. Among all alloying elements, Cr shows the most significant promoting effect, with the relative density of the Cu-0.5 wt% Cr sample being increased to 95% after sintering, about 5% higher than the pure Cu sample. Both the thermodynamic analysis and microstructure observation of the sintered samples suggest that the sintering enhancement can be attributed to the reduction of oxide layer on the Cu powder. The sintering-promoting elements are more affinitive to oxygen. Therefore, they are more likely to react with the oxide layer on the powder surface and facilitate the sintering.