Effect of ball milling on structural characteristics of tungsten powder

Abstract

The effect of the tungsten powder ball milling time (up to 48 hr) on such powder characteristics as the particle size and shape, composition, specific surface area as well as the substructural parameters has been investigated. An efficient refining of the powder was shown to take place only at the initial stages of milling (to 8 hr) and to be accompanied by a sharp increase in the level of stresses in the particles, namely to 1,2 GPa. The XRD patterns indicate that in the course of milling accumulation of randomly distributed dislocations occurs, which are responsible for stresses of type 2, with the contribution of the regions of coherent scattering into the broadening of dispersion curves being insignificant. The further milling led to the powder approaching the dynamic equilibrium along with simultaneous dispergation and agglomeration of particles, which was shown up by stabilization of both the particle size (and the specific surface area) and the level of microstresses in particles. Full text download