Contamination-free fabricating TiAl–Ta alloy by tantalum crucible smelting TiAl alloy

To solve the contamination problem of smelting TiAl alloy with the traditional ceramic crucibles, metal Ta crucible is preferred to smelt TiAl alloy to obtain TiAl–Ta alloy without any contamination. This study shows that three layers (about 10 μm thickness), namely the Ta(ss) layer, Ta(ss) + (Ta,Ti)₂Al layer and (Ta,Ti)₂Al layer, formed on the inner surface of the Ta crucible contribute to protecting Ta crucible from further erosion, while a stable boundary layer produced in TiAl alloy melt is beneficial for stabilising the composition of TiAl–Ta alloy. After the stable interfacial layer is established, the quantitative relationship between the dissolution thickness of Ta crucible and the increase of Ta content in TiAl–Ta alloy is established, making sure that the quantitative control of tantalum alloying of titanium aluminium alloy. This work offers experimental and theoretical fundamentals for practical application of contamination-free fabricating TiAl–Ta alloy in aerospace field, and provides a novel technique that can be adopted to prepare similar alloys without contamination.