Flaking behavior and microstructure evolution of nickel and copper powder during mechanical milling in liquid environment

To prepare metal flakes with a high flaking level and investigate the microstructure of metal flakes, nickel and copper powder were mechanically milled in liquid environment and the microstructure of powders was investigated by X-ray diffraction. The milling process can be divided into flaking and broken stages. At the flaking stage, milled metal powders exhibited high flaking level and flaky microshape, and 〈2 0 0〉 became preferred orientation. While at the broken stage, the milled powders presented a low flaking level and irregular microshape, and 〈2 0 0〉 was not preferred orientation any longer. The grain size, microstrain and dislocation density along 〈2 0 0〉 direction varied with milling time differently from that along 〈1 1 1〉 direction. The flaking level of the milled powders was related to the 〈2 0 0〉 preferred orientation, and more closely to the deformation mechanism. We can strengthen the formation of 〈2 0 0〉 preferred orientation to obtain metal powders with a high flaking level.