Effect of process control agent on the synthesis of Cu-Y2O3 by mechanical alloying

Two types of Cu composites containing 3 wt% Y2O3, with and without a process control agent (PCA), were fabricated using mechanical alloying (MA) and hot isostatic pressing (HIP). The results showed that the addition of PCA effectively inhibited the growth of MA powders. This was attributed to the PCA forming a lubricating film on the MA powders, preventing adhesion between the powders. However, residual PCA after heat treatments contained C impurities, which had a significant impact on thermal conductivity. The lubricating film weakened the binding force between MA powders during sintering, resulting in poor mechanical performance. Additionally, the lubricating film slowed down the MA process by eliminating the frictional stress caused by oblique collision. Frictional stress plays a crucial role in the dissolution of Y into the Cu matrix due to the tearing of Y-rich particles and the fracture of MA powders. Therefore, it is necessary to explore an optimum PCA that can be easily removed before sintering, slow down the growth of MA powders, and avoid reducing the efficiency of the MA process during the synthesis of Cu-Y2O3 composites by mechanical alloying.