High-temperature ablation behavior and microstructure evolution mechanism of W-4Re-0.27HfC alloy in plasma flame environment

The high-temperature ablation behavior and microstructural evolution mechanism of the W-4Re-0.27HfC alloy were investigated using a plasma flame ablation test (PFAT). It was found that the mass ablation rate and the linear ablation rate of W-4Re-0.27HfC at 2800 °C were determined to be only 2.71 × 10 2 mg/s and 1.98 × 10 −2 mm/s, respectively. Ablation products consisting of HfO₂, WO₃, Re₂O₇, WC, and HfW 2 O 8 were observed on the surface. In the ablation process, HfC was preferentially oxidized to form HfO 2 , which covers the surface of the oxide layer, effectively blocking the transfer of heat and O₂. Then, W was preferentially oxidized than Re to generate WO 3 . Notably, Re in the oxide layer still remained unoxidized and segregated in the form of dendrites, demonstrating that Re has stronger oxidation resistance compared to W and HfC. The improvement of ablation resistance through enhancing the oxidation resistance of W alloys by adding Re was verified for the first time in high-temperature ablation process. • The products of the W-4Re-0.27HfC alloy after plasma flame ablation were WO 3 , HfO 2 , Re 2 O 7 , WC, and HfW 2 O 8 . • HfC was oxidized to form HfO 2 , which was enriched on the surface of the oxide layer, serving to insulate against oxygen and heat. • In the oxide layer, Re was not completely oxidized, and a substantial amount of Re and Re 2 O 7 existed in the form of dendrites. • The improvement of ablation resistance through enhancing the oxidation resistance of W alloys by adding Re was verified for the first time.