Design and mechanical properties of Mo-10Si-7B alloys doped with lanthanum oxide by a hot pressing process

Abstract

Mo-10Si-7B alloys doped with different mass fractions (0.3, 0.6, 0.9, and 1.2 wt%) of lanthanum oxide (La2O3) were prepared by liquid-liquid doping, mechanical alloying, and hot pressing. The obtained alloys have shown a fine-grained structure comprising of α-Mo, Mo5SiB2, and Mo3Si phases. The microstructures of the Mo-10Si-7B alloys revealed that their grains became finer with an increase in the content of La2O3. The maximum bending strength of Mo-10Si-7B alloys (1.48 GPa) was obtained upon doping with 0.9 wt% La2O3. The fracture toughness of the corresponding alloys was ∼15.58 MPa·m1/2, indicating that La2O3 through liquid-liquid doping significantly improved the bending strength and fracture toughness of doped alloys compared to un-doped alloys. Also, the densities of the obtained alloys were relatively high, mainly due to hot pressing, which reduces the porosity, micro-cracks, and other defects.