Achieving high transverse rupture strength of WC-8Co hardmetals through forming plate-like WC grains by plasma assisted milling

WC-8Co hardmetals with prismatic WC grains and plate-like WC grains were respectively produced through sintering the W-C-8Co elemental powder mixture, prepared by dielectric barrier discharge plasma assisted milling (denoted as DBDP-milling). The results show that the microstructure, hardness and transverse rupture strength (TRS) of the sintered hardmetals are related to the morphology and size of milled W, which is dependent on the DBDP-milling time. When using W of different particle sizes as raw materials, prismatic WC grains of corresponded different size tend to form in the DBDP-1h milled W-C-Co powders contain granular W particles. While the DBDP-3h milled powders contains flake-like W flakelets that generate plate-like WC grains with different degree of preferential orientation when the size of raw W materials are different. Compared with triangular prismatic WC, a suitable range of the degree of preferential orientated plate-like WC in hardmetals has the advantage for improving the TRS while maintaining excellent hardness.