Binder Phase Structure in Fine and Coarse WC-Co Hard Metals with Cr and V Carbide Additions

摘要

The structure of the binder phase has been imaged in fine (＜ 1 μm) and coarse (＞ 2 pm) grained hard materials using Orientation Image Mapping (OIM).From OIM,the effect of grain size and composition on the binder phase can be observed.This work shows that the hcp phase present in Co binder consists of small (～1 μm) islands dispersed within the dominant fcc binder structure.Ratios of hcp and fcc-structured Co were observed to vary with composition and grain size with fcc dominating for all sub-micron WC samples.Vanadium was the most effective grain size inhibitor and had the most effect at supressing the formation of the hcp Co phase.A weak correlation with the suppression of the hcp phase and the cobalt magnetic moment CoM was also observed.Composition was also observed to affect the dispersion and the size of the fcc Co super-regions.It is intended that more information on the binder phase will aid future modelling and exploration of WC-Co hard materials.