Effect of La₂O₃ Addition on the Microstructure and Mechanical Properties of TiC-Based Cermets

TiC-based cermets with four different components of La2O3 content were prepared via vacuum sintering to investigate the effect of La2O3 addition on the microstructure and mechanical properties. The microstructure and phase structure were investigated by XRD, SEM, EDS and the mechanical properties were measured. Experimental results show that TiC-based cermets with La2O3 addition were also a typical core-rim structure but did not form a new phase. Along with the increase of La2O3 content, the density of TiC-based cermets was reduced, EDS analysis revealed La2O3 was partly dissolved in the Mo/Ni binder and hindered dissolution and separation of carbides. A moderate amount of La2O3 can favor the microstructure refinement and improve its mechanical properties in the form of La2O3 particles embedded in Mo/Ni particles. Compared with undoped sample, the cermets doped with 1 wt.% La2O3 showed optimum comprehensive properties: the bending strength of 1041.4 MPa, Vickers hardness of 13.19 GPa and the fracture toughness of 14.18 MPa• m1/2.