Investigations on the formation of multi-modal size distribution of mechanochemically processed Cu-Y-CuO powders

Abstract

Abstract In order to improve the high-temperature stability of copper (Cu) alloys, which have a range of applications because of their high conductivity, an in-situ mechanochemical process based on Mechanical Alloying (MA) and Hot Isostatic Pressing (HIP) was proposed and Cu-Y2O3 alloys were prepared. An interesting multi-modal distribution of particle size was observed in the high yttria (3/ 5 wt%) doped MA powders. Understanding the mechanism behind the above phenomenon will be important for preparing ODS-Cu by MA process. Thus, this paper investigates the formation of multi-modal distribution of particle size in the Cu-Y-CuO system. It was found that the finer the powder, the larger its lattice parameter, hardness, and oxygen content will be. On the basis of these data and the microstructural evolution of the powders with MA time, it was suggested that after CuO powder is mixed with Cu-Y alloyed powder, the high energy ball-milling will induce the formation of a hard and brittle O-rich shell on the surface of Cu-Y particles. With the continuing of MA, the high-energy collision between the balls will make the hard/brittle O-rich layer break into pieces. These results can provide helpful information to optimize the preparation of copper-based materials through process control.