Effect of La_2O_3 Addition on the Microstructure and Mechanical Properties of TiC-based Cermets

摘要

TiC-based cermets with four different components of La_2O_3 content were prepared via vacuum sintering to investigate the effect of La_2O_3 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 La_2O_3 addition were also a typical core-rim structure but did not form a new phase. Along with the increase of La_2O_3 content, the density of TiC-based cermets was reduced, EDS analysis revealed La_2O_3 was partly dissolved in the Mo/Ni binder and hindered dissolution and separation of carbides. A moderate amount of La_2O_3 can favor the microstructure refinement and improve its mechanical properties in the form of La_2O_3 particles embedded in Mo/Ni particles. Compared with undoped sample, the cermets doped with 1 wt.% La_2O_3 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·m~(1/2).