Different Ball Milling Time Effect on Tungsten Copper Powder Phase

With increasing milling time, milling process leads to undergo refinement Cu diffraction peak intensity decreases, but equal to reduce diffraction peak intensity of W. Under the same conditions as observed, it can still be clearly observed diffraction peaks of Cu, Cu and the second peak has disappeared. This explains the grain refinement is not mechanical alloying process MA W, times the diffraction peaks disappear Cu sample of the main reasons. In the process of ball milling, tungsten copper W-Cu powder solid state reaction occurred, which leads to Cu content with fcc structure so that diffraction peaks disappeared is the main factor.

Viewed from the distance of grains and diffraction angle, with the increasing ball milling time, the distance of grains extend, the angle of diffraction decrease. It suggests that in the process of milling grain refinement occurs and is accompanied by solid solution phenomenon, whereas in solution process, a small amount of copper Cu diffusion into the tungsten W phase, and form solid solution. This is due to the high energy ball milling process, tungsten-copper composite powder produced severe plastic deformation in the ball rolling, cold rolling and cropping intensity, the particles undergone great stress and strain, resulting in grains forming a large number of dislocations, distortions and other microscopic defects, microscopic strain increases and a large number of dislocations tangles, and to promote the formation of sub-cellular structures and lead to reduced grain size. In addition, a large number of grains of crystal defects easily make atomic activity and increased energy storage system, promote the formation of a solid solution.

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