Comparative study of microstructural evolution in W-3Re alloy under high-temperature conditions: High heat flux loading versus furnace heating

In tokamak devices, tungsten (W), as the main candidate for plasma facing material, will suffer from the simultaneous challenges of high heat flux (HHF) and neutron irradiation. This study involved annealing experiments on W-3Re alloy using two distinct heating methods: furnace heating and electron beam heating. The evolution of hardness and microstrure of tungsten-rhenium (W-3Re) alloy after isochronous annealing and isothermal annealing has been analyzed and compared with pure tungsten (PW). The recrystallization kinetics of W-3Re alloy have been obtained employing the Johnson Mehl-Avrami Kolmogorov (JMAK) equation. Experimental results showed that recrystallization kinetics during electron beam annealing were faster than those in furnace annealing. This phenomenon can be attributed to the rapid heating process of electron beam annealing, which preserved more deformation energy within the material, thus providing more driving force for recrystallization at high temperatures. Additionally, Re appeared to inhibit grain boundary migration in W-3Re alloy, causing the recrystallization temperature to be approximately 100 degrees C higher than in pure tungsten, and also resulted in a smaller average grain size compared to pure tungsten. This research provides experimental data and reference for predicting the microstructural evolution of tungsten-rhenium alloy in future fusion reactor environments.