On the reaction sequence of WC-Co formation using an integrated mechanicaland thermal activation process

A systematic study on the reaction sequence of WC-Co composite formation by annealing high energy ball milled WO3, CoO and graphite powder mixtures in a hydrogen atmosphere has been conducted. X-ray diffraction has been used as the main tool to analyze the phase transformation of the powder mixture during processing. It was observed that WO3 is reduced to W phase by passin g through the intermediate W20O58 and WO2 phases and the subsequent carburi zation sequence appears as W --> Co6W6C --> Co3W3C -->W2C --> WC. The inter mediate Co3W has been found in the reduction stage, which can be subsequent ly carburized at higher temperatures. (C) 2001 Acta Materialia Inc. Publish ed by Elsevier Science Ltd. All rights reserved.