Effect of carbon on the microstructure and element distribution in Ti42Al5Mn alloy

Abstract

The role of C on microstructure and local chemical composition of an as-cast Ti42Al5Mn alloy was systematically characterised. Results show that C is enriched in α₂, less dissolved in γ but depleted in β_o phase. Crossing the C-solubility limit, approximately 0.3 at. %, leads to the precipitation of h-type carbides (Ti₂AlC). Furthermore, a correlation between the lattice site preference and the C-solubility is rationalised by neutron powder diffraction technique, suggesting that Mn tends to substitute the position of Al site within the γ-phase (L1₀-lattice) with an occupancy rate of 4.31%. Consequently, fewer Ti₆-type sites are formed where C is preferentially located. Finally, the interlamellar spacing and phase evolution as well as the preferential distribution of alloying elements are also evaluated.

KEYWORDS:

• γ-TiAl
• Carbon
• microstructure
• solubility
• Ti₂AlC
• phase evolution
• element distribution
• neutron powder diffraction

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (No. 51971215), the National Natural Science Foundation of Liaoning province (No. 2019-MS-330) and the China Postdoctoral Science Foundation (No. 2019M661152). The authors also thank Professor Shunnan Zhang for valuable discussions.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China [grant number 51971215], the Natural Science Foundation of Liaoning Province [Grant munber 2019-MS-330] and the China Postdoctoral Science Foundation [grant number 2019M661152].