| Effects of the grain size and the nonequilibrium state of grain boundaries (GBs) on the local atomic structure, energy and stress fields in nanocrystalline materials are studied separately on a quasi-two-dimensional model of nanocrystals containing special tilt grain boundaries. In the ground state characterized by equilibrium GBs, the average specific GB energy of nanocrystals is shown to be independent of the grain size. An excess volume introduced into GBs in initial systems results in nonequilibrium GB structure in relaxed nanocrystals and produces a significant effect on the average energy and stress fields of GBs. The results of this study indicate the importance of a correct construction of initial structures for molecular dynamics simulations of nanocrystals, which should account for nonequilibrium state of GBs introduced during the preparation of nanocrystals. |
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