Preparation and properties of sintered molybdenum doped with La2O3/MoSi2

Sintered Mo with the addition of La2O3/MoSi2 was prepared via the process of solid-solid doping + powder metallurgy. X-ray diffraction experiment, hardness test, three-point bending test and high-temperature tensile test were carried out to characterize the samples. The XRD pattern of a typical sample shows that the sintered Mo was mainly composed of Mo, La2O3 and Mo5Si3. Mo5Si3 was probably formed through the reaction between MoSi2 and the Mo matrix. Densities and fracture toughnesses of both doped Mo and pure Mo were measured and contrasted. Sintered Mo with the addition of 0.2 wt% La2O3/MoSi2 has the highest toughness, while more addition of La2O3/MoSi2 has smaller effect on improving toughness or even embrittles Mo. The results of three-point bending test and high-temperature tensile test show that the bending strength and high-temperature tensile strength of doped Mo are both higher than those of pure Mo. The formation of Mo5Si3 improves the high-temperature strength. The La2O3/Mo5Si3 dispersed in the Mo matrix refined the grains, and thus strengthened the Mo matrix by dispersion strengthening and grain refinement.