HAADF-STEM observations illustrate that the probabilities of appearance of (111) microtwins with different twinning structures in μ phase were different. Based on this, 8 possible (111) twinning models with different twin boundary structures are established and discussed via DFT. Experimental characterization and DFT calculations reveal a close relation between the probabilities of appearance of these (111) microtwins and the interface energy at the twin boundaries: the smaller the energy is, the easier the twinning structure is to form and exist stably. TB5, with the smallest interface energy, is exactly the abundantly-existing twinning structure observed in HAADF. Moreover, via DFT simulation, distribution behaviors of the solute elements Cr, Mo, Re, Ni at the twin boundary of TB3 and the atomic arrangement at (111) twin boundary of C15–Cr2Nb crystal have been predicted and analyzed. The methods of DFT simulation and analysis on the twin boundaries provide a new strategy to study the twinning structures of complex-structured crystals and preferred distribution of different solutes at the twin boundary, etc.
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