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 < 111 > 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. (c) 2007 Elsevier B.V. All rights reserved.