Grain refinement mechanism of boron addition within Ti-Al alloy

B Zhai and J Chang and GX Li and HP Wang, APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 130, 106 (2024).

DOI: 10.1007/s00339-024-07277-1

To better understand the effects of B addition on the grain refinement mechanism of Ti-Al-based alloys, we investigate liquid local structure, nucleation and liquid/solid interface migration of Ti-Al-B alloy using molecular dynamics with a deep neural network potential. It is found that Ti/Al and B atoms repel each other, and the order structure is decided by Ti-Al bonds in the dilute B solution. B atoms are not involved in the formation of short-range-order structures or the growth of beta crystals. The production of borides occurs at the frontier of liquid-solid interface, depending on the presence of a rich-B liquid phase caused by the L -> beta phase transition. It is indicated that constitutional undercooling causes the grain refinement of Ti-Al-based alloys by B addition.

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