Tilt grain boundaries energy and structure in NiTi alloys
F Yazdandoost and R Mirzaeifar, COMPUTATIONAL MATERIALS SCIENCE, 131, 108-119 (2017).
Energy and structure of tilt grain boundaries are studied in Nickel- Titanium (NiTi) alloys. Molecular dynamics (MD) simulations are utilized to investigate the excess energy of symmetric and asymmetric tilt grain boundaries as a function of the misorientation and inclination angles. Structural units of different symmetric grain boundaries are identified and the correlation between the structure and energy is investigated. It is shown that the Read-Shokley model can accurately predict the energy of low angle symmetric tilt grain boundaries in austenite NiTi alloy. Density functional theory (DFT) calculations are used to study two representative symmetric grain boundaries. Comparing to DFT calculations, it is shown that the MD results can predict the GB potential energies accurately. The Electron charge density distributions are studied and the bonding strength between atoms, and low/high charge density regions are investigated, and accosted with the structural units in the grain boundaries. It is shown that a symmetric arrangement of Ni and Ti atoms at the GB improved the uniformity of bonding and charge density distribution. (C) 2017 Elsevier B.V. All rights reserved.
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