Ti(C,N)‐based cermets with strengthened interfaces: Roles of secondary cubic carbides

Abstract

Core‐rim structure, concerning its interface structure and internal stress, plays an important role in mechanical performance of Ti(C,N)‐based cermets. Four types of cermets containing equimolar TaC, VC, ZrC, and NbC were fabricated, in order to reveal the synergetic relationship between core‐rim structure and mechanical properties. VC and ZrC effectively inhibited the grain growth, while TaC and NbC favored for coarser core‐rim grains. A thin distortion layer at the rim‐binder interface was confirmed, formed during the solidifying stage. Compared to the TaC, ZrC and NbC, VC shrunk the lattice parameters of rims and effectively decreased the lattice misfit of the distortion zone from around 4.0%‐0.8%. Cermets containing VC showed satisfactory bending strength of 2099 MPa and toughness of 10. 3 MPa m1/2, owing to the strengthened rim‐binder interface. TaC and NbC exhibited the similar roles in cermets with comparable mechanical properties, while addition of ZrC increased the lattice misfit of core‐rim structure, resulting in poor mechanical performance. Decreased lattice misfit of rim‐binder interface changed the fracture mode of cermets from intergranular to transgranular fracture, with in‐situ formed dimples.

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

“…It can be seen from Figure 9B,C and Figure S7A1-3,B1-3 that the core-inner/outer rim boundary shows an obvious coherent relationship with the misfit of 0.1%−0.2%, which is half lower than the reported 0.3%−1.5% in References. 43,50 The straight interface between the hard phase and binder phase as shown in Figure 9F and Figure S7D1-3 are similar to these in previous cermets. [42][43][44]50 According to these reports, there are usually deformation zones in 3-5 atomic layers thick with a certain deviation angle at the interface between the two phases.…”

“…43,50 The straight interface between the hard phase and binder phase as shown in Figure 9F and Figure S7D1-3 are similar to these in previous cermets. [42][43][44]50 According to these reports, there are usually deformation zones in 3-5 atomic layers thick with a certain deviation angle at the interface between the two phases. But, no significant deflection angle is found at the interface of our (Ti, W, Mo, Cr) (C, N)-based cermets.…”

“…The (A) densities and (B) mechanical properties of the (Ti, W, Mo, Cr)(C, N)‐based cermets sintered at different temperatures, (c) properties comparison for the present cermets and literature data 16,17,24,29,30,33,34,42–53 …”

“…Porosity levels are higher than A04B00C00 except for that of cermets sintered at 1380 • C, which means that the sintering process could complete densification. With the temperature increasing, TRS firstly increases and then decreases, hardness shows the same tendency, but finally increases at 1460 16,17,24,29,30,33,34,[42][43][44][45][46][47][48][49][50][51][52][53] .…”

“…The high hardness at 1460 • C and fracture toughness at 1440 • C both contributed to the volatilization of the binder phase and the grain growth of the hard phase. Figure 5C gives the comparison of the hardness-K IC -TRS for our cements and reported ones, 16,17,24,29,30,33,34,[42][43][44][45][46][47][48][49][50][51][52][53] in which the hardness is tested by Vicker's hardness with loads of 0.02-30 Kgf. The concrete values for more mechanical properties comparison are shown in Tables S4 and S5.…”