A study of grain-boundary structure in non-stoichiometric NiAl by atomistic simulation and electron microscopy

摘要

The atomic structure of a Sigma = 5, (310)[001] grain boundary in NiAl has been determined by a synergistic approach using high-resolution electron microscopy (HREM) and atomistic structure calculations. The effect and distribution of point defects at the grain boundary were determined using molecular statics calculations employing N-body empirical potentials to calculate the relaxed grain-boundary structures and energies resulting from various initial structures and stoichiometries. Monte Carlo calculations confirm the stability of the lowest-energy structure, which contains Ni antisite defects adjacent to the grain-boundary plane. Multislice image simulations of this structure are in good agreement with the experimental HREM image. This is the first combined application of experimental and theoretical structure determinations to an intermetallic grain boundary.