Effect of thermomechanical circulation in short-time on cobalt binder phase in WC-20 wt%Co

The structural aviation in response to cobalt binder phase of WC- 20wt%Co cemented carbides has been investigated under the conditions of cyclic temperatures or cyclic compressive stress and composite of temperature-stress cycling in short-time for three states of specimens, i.e. sintered, quenched and tempered states. It is shown that the relative volume fraction of beta-Co (fcc) in cobalt binder all decreases after variety of circulation, whereas that of epsilon-Co (hcp) increases correspondingly. In conventional sintering cemented carbides, the variation of beta-Co content decreases progressively as following cyclic temperature, cyclic stress and thermomechanical circulation. After thermomechanical circulation, among three-state of specimens, remained beta-Co content of as-tempered state is highest, that of as-quenched is medium, and that of as-sintered is lowest. The phase constituent of cobalt binder was strongly affected by thermomechanical circulation at 650 +/- 50 degrees C/20 double left right arrow 750 MPa (uniaxial compressive stress). (C) 1998 Elsevier Science Ltd. All rights reserved.