Introducing the High Entropy Concept for Cemented Carbides

Traditional cemented carbides are based on tungsten carbide (WC) as a hard phase and cobalt (Co) as metal binder phase. Due to issues regarding health, the safety in supply, and ethical sourcing of both W and Co, alternative compositions are of increasing interest. Since its introduction the high entropy concept has been applied to many areas in material development: Upon mixing five or more constituents in equal amounts to form a single phase a high state of disorder is created which can lead to unique properties of the novel material. This concept is now applied to novel high entropy carbide (HEC) hard phases and high entropy alloy (HEA) binder phases in cemented carbides. Different routes for producing HECs with different compositions were investigated and feasibility studies with conventional binder metals such as Co, Ni or FeNi were carried out. In addition, HEAs based on Mn, Co, Fe, Ni, and Cu were studied in cemented carbides with TiCN and WC as hard phases. Furthermore, trials with compositions combining HEC and HEA were successfully carried out. The resulting double high entropy based cemented carbide consists in total of ten metallic elements together with C, but comprises just one hard and one binder phase.