Achieving hardness‐strength‐toughness synergy in (Ti, W, Mo, Cr)(C, N)‐based cermets

Abstract

AbstractTi(C, N)‐based cermets have been considered to be the most potential candidates for WC‐Co cemented carbides as tool material due to their various advantages. However, the trade‐off between hardness/strength and toughness limits their further application. Herein, we present new (Ti, W, Mo, Cr)(C, N)‐based cermets showing superior mechanical properties with hardness of 1525 MPa, transverse rupture strength of 2428 MPa, and fracture toughness of 11.44 MPa·m1/2 by compositional and interfacial modification. The strengthening and toughening mechanisms were revealed by experimental observation and theory calculation. It could be clarified that the high elastic modulus caused by a polar covalent bond in the hard phase and solid solution strengthening of the binder phase attributed to the hardness. The strong interface bonding between the core/rim, inner/outer rim, and rim/binder phases stemming from the composition optimization contributed to super crack resistance. Intergranular fracture in submicron‐scaled hard phases led to the crack deflection, transgranular fracture in the micron‐scaled hard phases consumed more energy due to their high intrinsic hardness and excellent interface coordination. The synergy of multi‐scaled hard particles brought about excellent comprehensive mechanical properties.