The microstructure and properties of novel Ti(C,N)-based cermets with multi-component CoCrFeNiCu high-entropy alloy binders

Abstract In this study, mechanical alloyed (MA) and gas atomized (GA) CoCrFeNiCu high-entropy alloy (HEA) powders were utilized as binders to fabricate two kinds of novel Ti(C,N)-HEA cermets by vacuum sintering + low-pressure sintering. Compared with conventional Ni binder, both MA and GA CoCrFeNiCu binders have a huge superiority to the inhibition of core-rim grain growth and the formation of submicron white-coreless grains owing to the sluggish diffusion effects. Both Ti(C,N)-HEA cermets exhibit higher fracture toughness of 8.8 and 9.8 MPa m−1/2 and hardness of 1726 and 1580 HV than those of conventional cermet with Ni binder, respectively. The good co-enhancements of hardness and toughness result from the fine microstructures with less interfaces and CoCrFeNiCu binders with maximized solid solution strengthening effects. Besides, both Ti(C,N)-HEA cermets exhibit suitable transverse rupture strength of 1513 and 1768 MPa, respectively. At high temperatures, the high-entropy effects of CoCrFeNiCu binders stabilize bonding and lubrication to enhance wear resistance and wear reduction performances of Ti(C,N)-based cermets. The high-temperature wear rates and inter-steel friction coefficients of conventional Ti(C,N)–Ni cermet are basically 1.4 ∼ 2.4 times than those of novel Ti(C,N)-HEA cermets under the investigated conditions. Broadly, CoCrFeNiCu alloy exhibits good potential to be used as new binders in Ti(C,N)-based cermets.