Microstructural development of tungsten and tungsten–rhenium alloys due to neutron irradiation in HFIR

Abstract

The microstructural development of pure tungsten (W) and tungsten–rhenium (Re) alloys due to neutron irradiation in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, TN, USA, was investigated in this work. The irradiation conditions were ∼1 displacements per atom (dpa) at 500 and 800°C. After the neutron irradiation, microstructural observations were performed using a transmission electron microscope (TEM). Large amounts of precipitates identified as sigma- and chi-phases were observed in not only the W–Re alloys but also in the pure W after the neutron irradiation. The precipitates observed in the pure W were coarse and larger than those in the W–Re alloys. This was considered to be caused by the transmutation products of W and Re, namely, Re and osmium (Os), respectively, under irradiation in the HFIR with a higher contents of thermal neutron flux.