Microstructure evolution of carbon doped Ta-W-Hf alloy by hot forging and annealing

R Bai and S Zhang and L Huang and H Liu and F Wang and XM Cai and MX Xia and R Sun and H Wang and P Hu and W Zhang, MATERIALS CHARACTERIZATION, 229, 115588 (2025).

DOI: 10.1016/j.matchar.2025.115588

Ta-W-Hf based alloys (T-111 and ASTAR-811C) doped with various carbon contents ((0, 0.01 and 0.025 wt%) were fabricated via high-temperature vacuum sintering and electron beam melting, followed by thermal forging and annealing. Effects of carbon content on the microstructural evolution and carbide distributions in Ta-W-Hf based alloys was investigated in this study. Microstructural analysis revealed that carbon doping effectively refined the grain sizes of the as-forged TaWHf-0.025C alloy owing to the precipitation of carbides along grain boundaries. In contrast, the formation of carbides in the as-forged TaWHf-0.01C alloy was not pronounced. It was found that fine Ta2C particles formed and uniformly distributed in the grains of the TaWHf-0.01C alloy after annealing, whereas the carbides in the TaWHf-0.025C alloy remained predominantly located at grain boundaries. Furthermore, the interface between the Ta matrix and Ta2C with crystallographic relationships of 001matrix 1101Ta2C and (200)matrix (1011)Ta2C was identified, These findings highlight the role of carbon content in tailoring carbide distributions and interfacial coherence, which critically influence the mechanical properties and thermal stability of Ta-W-Hf based alloys.

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