High strength molybdenum alloy can be used in outer space nuclear reactor
Hefei institute of Physical Science, Chinese Academy of Sciences (CAS) has developed a high-performance molybdenum alloy in cooperation with China Nuclear Power Research and Design Institute, which may be used in advanced nuclear energy systems, aerospace and other fields, the institute said on February 24. The findings were published in Acta Materials, a journal of metal materials.
Space nuclear reactors have outstanding advantages such as good environmental adaptability, wide power coverage, compact structure and small mass power ratio under high power conditions, and have broad application prospects in high-power earth orbit satellites, deep space exploration and power supply for lunar and planetary bases. The cladding and core structural materials in space reactors face harsh service environment such as high temperature, neutron irradiation and liquid alkali corrosion, which is one of the bottlenecks restricting the development of space reactor technology. Molybdenum and its alloy are the key candidate materials for space reactor due to their advantages of high melting point, high thermal conductivity and good compatibility with alkali metals. However, pure molybdenum has some problems such as low ductility at room temperature, insufficient strength at high temperature, recrystallization brittleness and irradiation embrittlement.
The research team proposed that the comprehensive properties of molybdenum alloy can be improved through the diffusion of nano-carbide, fine grain strengthening and grain boundary purification. The research team prepared nano-structured Molybdenum zirconium carbide with excellent mechanical properties at room temperature and high temperature by powder metallurgy and high temperature rotary forging. The tensile strength of the nano-structured alloy at room temperature is 928 mpa and the elongation is 34.4%, which is 26% and more than twice that of TZM alloy. At 1000℃, the tensile strength of molybdenum-zirconium carbide alloy reaches 562 mpa, which is more than 50% higher than that of pure molybdenum and other nano-structured alloys. At 1200℃, the strength advantage of Mo-Zr carbide alloy is more obvious. The tensile strength of mo-ZR carbide alloy is more than twice as high as that of mo dispersed strengthened by oxide, while maintaining excellent plasticity. In addition, the recrystallization temperature of the alloy is about 400℃ higher than that of pure molybdenum, and it has excellent high temperature stability.
The results show that the nano-structured molybdenum-zirconium carbide alloy has excellent strength and toughness at room temperature and high temperature, which has obvious advantages over the similar materials reported.
