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 βo 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.
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).