Mechanochemical processing of Cu-Y2O3 alloy by MA-HIP for heat sink materials application

Fabricating high-strength copper (Cu) alloys with high conductivity are extremely desirable for a range of applications, such as heat sink materials in fusion reactors. This study reports an in-situ mechanochemical process combining Mechanical Alloying (MA) and Hot Isostatic Pressing (HIP) to prepare Cu-Y2O3 composites. It is found that MA of Cu and Y powders led to formation of a Cu(Y) solid solution, accompanied by lattice expansion, grain refinement, melting point decline, and hardness increase. When the Cu(Y) solid solution powder was milled with CuO powder, reaction between Cu(Y) and CuO occurred, with a shrinkage of the lattice, and increase in both the melting point and hardness. The MA powder was then consolidated by HIP, and the existence of Y2O3 was confirmed by X-ray diffraction. An unexpected decrease of the electrical conductivity of the consolidated bulk material was observed and the reason was analyzed. This study will provide helpful information to optimize the preparation of copper-based materials through process control.