Development of complex concentrated alloys binders for Co-free cemented WC composites

Cemented carbides such as WC–Co are widely used in industrial applications due to their excellent combination of properties, such as hardness, fracture toughness and wear resistance. However, in recent years, there has been increasing interest in partially or fully replacing cobalt as a binder because of concerns regarding its toxicity, price volatility and relatively poor corrosion resistance. One promising alternative is the use of complex concentrated alloys (CCAs), which have been identified in several studies as potential substitutes for Co. In this work, two CCAs (designated CCA1 and CCA2) were prepared and used as binders to produce Co-free cemented WC composites by pressureless sintering. The WC-CCA1 samples achieved a relative density above 95 % and hardness comparable to that of WC–Co. However, the presence of Al-rich oxides and η-carbide phases contributed to a significant reduction in fracture toughness compared with that of conventional WC–Co composites. Based on these results and thermodynamic calculations, a modified binder (CCA2) was developed and tested. The samples prepared with CCA2 exhibited relative densities between 88.9 % and 92.8 % (depending on the binder fraction and initial WC particle size) and showed microstructures consisting of WC grains uniformly surrounded by an FCC phase. No secondary phases were detected and samples exhibiting hardness-fracture toughness combinations within the range reported for WC composites prepared with Co or other alternative binders were obtained. Moreover, a significant improvement in corrosion resistance was observed compared with WC–Co composites. • Complex concentrated alloys (CCAs) designed to be used as binders for production of Co-free cemented WC composites. • WC–CCA samples exhibiting hardness-fracture toughness combinations within the range reported for WC–Co composites. • A significant improvement in corrosion resistance of WC-CCA samples was observed compared with WC–Co composites.