Unraveling High-Temperature Deformation Mechanisms in W and Alloys for Fusion Applications

This proposal aims to investigate the high-temperature deformation mechanisms and thermomechanical stability of tungsten (W) and W-Re alloys – two leading candidates for structural components in fusion reactors such as ITER and DEMO. These materials must withstand extreme operating conditions, including high temperatures, neutron irradiation, and mechanical loads. While rhenium (Re) additions are known to improve ductility and possibly enhance radiation tolerance, the fundamental mechanisms that govern this behaviour, particularly under service-relevant thermal and mechanical stresses, are not fully understood. We propose to use in-situ neutron diffraction on the Engin-X instrument at four key temperatures (room temperature, 500 °C, 750 °C, and 1000 °C) during uniaxial tensile loading. Neutron diffraction uniquely allows for non-destructive, bulk measurement of lattice strains, load partitioning, and dislocation activity in dense, coarse-grained refractory alloys. These experiments will yield mechanistic insight into how Re influences defect evolution and phase stability and will provide critical validation data for micromechanical modelling. Results will also contribute directly to fusion materials development and inform future design of more complex refractory alloys.