Abstract
In order to investigate the cause of the liquid phase migration (LPM) and the shape distortion when WC-Co cemented carbides (alloys) undergo a temperature gradient during cooling, round bars of WC-10 mass%Co alloys are inserted halfway under the coil of the induction heating furnace and partially heated at 1673 K. The results showed that Co migrated from the higher temperature side to the lower one and increase of Co content and bar diameter occurred in a zone at the outside of the coil. The alloy containing free carbon had a significantly narrow Co-increased zone and the zone located at a lower temperature. The volume transfer (V) of Co during heating changed in proportional to the square root of the heating time (t). It was considered that the phenomenon was the same as the LPM between a couple of alloys having different Co content in our previous report. We have concluded that the Co-increased zone in this study corresponds to the Co solid-liquid coexistence zone during partial heating and the Co increase is caused by the migration pressure occurred in the zone, which we named ΠSL. ΠSL should be generated because FWC/Co(S) derived from γWC/Co(S) and γCo(L)/Co(S) is higher than FWC/Co(L) derived from γWC/Co(L).
