In this study, lanthanum oxide (La2O3) dispersed molybdenum (Mo–La2O3) alloys are fabricated using lanthanum nitrate solution and nanosized Mo particles produced by hydrogen reduction of molybdenum oxide. The effect of La2O3 dispersion in a Mo matrix on the fracture toughness at room temperature is demonstrated through the formation behavior of La2O3 from the precursor and three-point bending test using a single-edge notched bend specimen. The relative density of the Mo–0.3La2O3 specimen sintered by pressureless sintering is approximately 99%, and La2O3 with a size of hundreds of nanometers is uniformly distributed in the Mo matrix. It is also confirmed that the fracture toughness is 19.46 MPa·m1/2, an improvement of approximately 40% over the fracture toughness of 13.50 MPa·m1/2 on a pure-Mo specimen without La2O3, and this difference in the fracture toughness occurs because of the changes in fracture mode of the Mo matrix caused by the dispersion of La2O3.

Over the last decade, the next generation’s ultra-high-temperature materials as an alternative to Nickel-based superalloys have been highlighted. Ultra-high-temperature materials based on refractory metals are one of several potential candidates. In particular, molybdenum alloys with small amounts of silicon and boron (Mo-Si-B alloys) have superior properties at high temperature. However, research related to Mo-Si-B alloys were mainly conducted by several developed countries but garnered little interest in Korea. Therefore, in this review paper, we introduce the development history of Mo-Si-B alloys briefly and discuss the properties, particularly the mechanical and oxidation properties of Mo- Si-B alloys. We also introduce the latest research trends of Mo-Si-B alloys based on the research paper. Finally, for domestic research related to this field, we explain why Mo-Si-B alloys should be developed and suggest the potential directions for Mo-Si-B alloys research.