Heat pipe reactor (HPR) is a newly designed solid-state nuclear reactor which removes the heat passively from the core to the secondary circuit or thermoelectric conversion device. Because of its simple design, inherent safety, easy operation and other advantages, HPR has attracted considerable interest as power source in exoplanet exploration, deep sea exploration, land-based power supply system and other application scenarios. Molybdenum-rhenium alloys are solid solution alloys derived by adding the element rhenium into pure molybdenum, and, unlike other molybdenum alloys, possess simultaneously excellent mechanical strength at high temperature and good processability at room temperature owing to their unique “rhenium effects”. In addition, molybdenum-rhenium alloys have been considered as the candidate materials for heat pipe reactor cores, especially for the space heat pipe reactor operating at extremely high temperatures, because of their excellent mechanical properties and good compatibilities with nuclear fuels like UO2, UN and UC, and alkali metal heat pipe coolants like Li, Na and K at high temperatures. Also, there's another advantage for molybdenum-rhenium alloys, i.e., the element rhenium could act as the spectral shift absorber which can improve the reactor's falling criticality safety. This review summarizes the research progress of molybdenum-rhenium alloys used in heat pipe reactor from the perspectives of chemical compositions and crystal structures, manufacture processes, thermal and physical properties, mechanical properties and other out-pile properties. The neutron irradiation behavior, irradiation properties, compatibilities with nuclear fuels and alkali metal heat pipe coolants and other in-pile application properties of molybdenum-rhenium alloys are introduced in detail as well. The paper ends with a prospective analysis about the challenging issues and the future research directions. © 2023 Cailiao Daobaoshe/ Materials Review. All rights reserved.
