Molybdenum (Mo) as a refractory metal has excellent high-temperature strength, good thermal conductivity, and low thermal expansion coefficient, and is widely used in aerospace, nuclear industry, electronic devices, and high-temperature structural materials. However, under extreme high-temperature conditions, the mechanical properties of pure molybdenum will significantly decrease, and therefore, alloying to improve its high-temperature strength has become a hot topic of research. Molybdenum alloys can maintain high strength and stability at high temperatures by adding different alloying elements and optimizing the preparation process, thus meeting the needs of modern industry for high-performance materials.



Firstly, the improvement of high-temperature strength in molybdenum alloys mainly relies on the solid solution strengthening mechanism. Common alloying elements include titanium (Ti), zirconium (Zr), hafnium (Hf), and rare earth elements. These elements can dissolve in the molybdenum matrix, causing lattice distortion and hindering dislocation movement, thereby improving the material's strength. For example, the Mo-0.5Ti-0.1Zr alloy exhibits good comprehensive mechanical properties at high temperatures, where titanium and zirconium not only play a solid solution strengthening role but also improve the material's oxidation resistance.



Secondly, precipitation strengthening is another important means to improve the high-temperature performance of molybdenum alloys. By adding elements such as carbon (C) and silicon (Si), dispersion-distributed carbides or silicides, such as Mo₂C and MoSi₂, can be formed in the molybdenum matrix. These fine precipitated phases uniformly distributed in the matrix can effectively prevent dislocation slip and enhance the material's high-temperature creep resistance. Especially under high-temperature conditions, the precipitated phases can exist stably, thus maintaining the material's high strength.



In addition, molybdenum alloys can also improve their high-temperature strength through grain refinement. The mechanism of fine grain strengthening lies in the increase in the number of grain boundaries, which can hinder dislocation movement and thus improve the yield strength of the material. By using advanced processes such as powder metallurgy, mechanical alloying, and heat treatment, fine and uniform grain structures can be obtained, further enhancing the high-temperature mechanical properties of molybdenum alloys.



It is worth mentioning that molybdenum alloys also face issues such as oxidation and brittleness at high temperatures. Therefore, in recent years, researchers have modified molybdenum alloys through surface coatings, composite material design, and other methods to extend their service life. For example, coating molybdenum alloys with silicides or ceramic coatings can effectively improve their oxidation resistance and thermal shock resistance.



In summary, molybdenum alloys can effectively improve their strength and stability under high-temperature environments through reasonable alloy design, the application of strengthening mechanisms, and the adoption of advanced processes. With the continuous development of high-tech fields such as aerospace and nuclear energy, the research and application prospects of molybdenum alloys will be even broader. In the future, the development of new molybdenum alloys with higher strength, better oxidation resistance, and superior workability will be one of the important directions in material science research.