One of the important characteristics of solid-state phase transformations in steels is the choreography of atoms as they traverse the frontier between the parent and the product phases. Some transformations involve a chaotic motion of atoms consistent with long-range diffusion, and hence are closer to equilibrium than those that where a disciplined transfer occurs. Since the pattern of atoms changes during transformation, a disciplined motion of atoms necessarily leads to a change in the shape of the transformed region, and like any deformation, such changes cause strains in the surrounding material. These displacive transformations are therefore strain dominated, with the morphology, chemical composition and thermodynamic framework sensitive to the strain energy due to the shape change. Here we consider the published data that have been accumulated on the displacements associated with `bainite', a phase transformation product in steels that forms the basis of the world's first bulk nanocrystalline metal.
Banaras Metallurgist 19 (2014) 1-7.
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