Molybdenum-Rhenium alloy: A focused review of strengthening-toughening mechanism and method

Due to the excellent high-temperature strength, radiation resistance, and deformation capacity, Molybdenum-Rhenium (Mo-Re) alloys have critical application in the nuclear industries and aerospace fields, etc. This paper systematically reviews the research on Mo-Re alloys by timelines, focusing on strengthening mechanisms, preparation techniques, multi-scale simulations, and engineering applications. Studies have demonstrated that the "rhenium effect" significantly enhances the mechanical properties of Mo-based alloys, with solid-solution strengthening, grain boundary purification, twin deformation, and phase-transformation strengthening. Advances in powder metallurgy, mechanical alloying, and additive manufacturing have also provided effective pathways for alloy designing. The synergistic application of multi-scale computations, such as first-principles calculations, machine-learning potentials, and phase-field simulations, has deepened the understanding of micro-mechanistic behaviors. Notably, current research harbors several critical gaps: (i) the micro-mechanisms underlying the peak ductility of low Re alloys remain need thoroughly elucidated; (ii) the radiation damage behavior and phase-transformation kinetics of high Re alloys necessitate further exploration; (iii) the hot-zone embitterment issue in welding processes demands urgent resolution; (iv) a model linking composition, processing, and performance is still lacking. Future investigations should prioritize the development of novel low Re high-toughness alloys designs and preparation, establishment of multi-field coupled performance prediction models, optimization of low-cost fabrication techniques, and development of in-situ characterization to reveal the deformation mechanisms. This review aims to offer theoretical guidance for the future-depth research, not only consolidates a century of insights but also provides a roadmap for next-generation refractory alloys.