Recently, the Industrial Technology Research Institute has made important progress in the strengthening and toughening of body-centered cubic refractory metals, and the pure molybdenum materials developed by the institute show unique recrystallization room temperature superplasticity after annealing at 1000~1700 °C ultra-high temperature, breaking through the traditional industry cognition of recrystallization brittleness of body-centered cubic refractory metals. Some of the research results were published in the form of papers in the top international academic journal Nature Communications (IF=16.6) (DOI: doi.org/10.1038/s41467-023-44056-7).
The research results were jointly completed by the State Key Laboratory of Intelligent Sensing Functional Materials of China, the State Key Laboratory of Nonferrous Metal Preparation and Processing, Zhejiang University, Nanjing University of Science and Technology and other advantageous universities. Through a combination of powder metallurgy, Y-type hot rolling and heat treatment, the innovation team has prepared a fully recrystallized pure molybdenum material with room temperature superplasticity. By designing ultra-low oxygen concentrations at grain boundaries to eliminate the intrinsic grain boundary brittleness of molybdenum, and combining it with a high proportion of <110>//RD texture and small-angle grain boundaries, the orderly evolution of the intragranular dislocation network and the dislocation crossing at the small-angle grain boundary (≤15°) are realized. The synergistic effect of these factors greatly inhibited the intergranular brittle fracture tendency of molybdenum, and the highest total elongation at room temperature of 108.7% was obtained. This discovery reveals a new mechanism of superplastic deformation of refractory metals at room temperature, and provides theoretical support and feasible routes for the fabrication of refractory metals and alloys required for harsh application scenarios.
Body-centered cubic refractory metal has excellent high-temperature strength, but recrystallization brittleness will lead to serious failure of the material after service in high-temperature or ultra-high-temperature scenarios, so how to achieve the strength-plasticity synergy improvement at room temperature and high temperature has always been a common demand of the refractory metal industry, and it is also an international research hotspot in the field of high-temperature materials. Over the years, China Research Institute has been committed to the innovative research and development and engineering application of rare metal materials with structural and functional integration, and has achieved fruitful results. This technological breakthrough is a successful example of collaborative research between the innovation platform of China National Research Institute and advantageous universities to solve common problems in the industry, and will play an important role in promoting engineering technology research and basic theoretical research in related fields.
