Strengthening and toughening of Ti(C,N)-based cermets: (Ti,W)C additive design and the mechanism

Abstract

(Ti0.88W0.12)C solid-solution is characterized by the lowest formation energy and hence it can significantly affect the microstructure and properties of Ti(C,N)-based cermets. This research aims to explore the design principle for (Ti0.88W0.12)C addition amount, and the related strengthening mechanism. 28TiC0.7N0.3–35(Ti0.88W0.12)C–4.5TaC–4.5NbC–8Mo2C–10Ni–10Co (A) and 48TiC0.7N0.3–15(Ti0.88W0.12)C–4.5TaC–4.5NbC–8Mo2C–10Ni–10Co (B) were prepared. On considering the application market expansion, the effect of TiC0.7N0.3/(Ti0.88W0.12)C ratio on the microstructure, mechanical properties and corrosion resistance was investigated. The results show that the hard phase in the two cermets exhibits a preferred orientation of (111) plane. Compared with cermet A, cermet B is characterized by a more uniform microstructure, finer hard phase grains, and 1.23 times higher transverse rupture strength (TRS). Hardness, Palmqvist toughness and TRS of cermet B are 90.5HRA, 12.1 MPa m1/2 and 2616 MPa, respectively. Hardness and toughness of cermet A are 0.4 HRA and 1.06 times higher than that of cermet B, respectively. The results of electrochemical corrosion experiments in H2SO4 (pH = 1) and NaOH (pH = 13) solutions show that cermet B exhibits better corrosion resistance. Both the cermets exhibit excellent resistance to NaOH solution corrosion. The strengthening mechanism driven by TiC0.7N0.3/(Ti0.88W0.12)C ratio is discussed.