Formation and growth of transition metal carbides in ferrite

RJ Slooter and MHF Sluiter and WGT Kranendonk and C Bos, COMPUTATIONAL MATERIALS SCIENCE, 242, 113097 (2024).

DOI: 10.1016/j.commatsci.2024.113097

Carbide nano-precipitates are commonly used to improve mechanical properties of steel. It has been experimentally observed that TiC, NbC, and VC carbide precipitates initially form as 'plate-like' particles oriented in the 100 planes of the ferrite lattice. These platelets share similarities with Guinier-Preston zones in Al-Cu alloys. The clustering of group IV and V transition metal atoms (M = Ti, Zr, Hf, V, Nb, Ta) in ferrite is studied using density functional theory. It is deduced that the transition metal carbides all form in a similar way. Furthermore, the transition from an initial M-C cluster to a NaCl- structured platelet to a NaCl-structured precipitate is examined through atomistic simulations using Modified Embedded Atom Method potentials. A route is established along which transition metal carbides form and transform into precipitates that possess the Baker-Nutting orientation relation with the ferrite matrix.

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