The atomic structure of the (310)[001] symmetrical tilt boundary in B2 ordered alloys was studied at 0K by means of numerical simulations using n-body empirical potentials. The high degree of order made the coincidence site lattice theory a valid approximation to grain boundary crystallography. The stable grain boundary variants were close to symmetrical and pseudosymmetrical coincidence site lattice models, with no grain-boundary vacancies. The extension to interfaces, of the independent point defect approximation which was rigorous for bulk ordered compounds, revealed a strong dependence of the grain boundary properties upon non-stoichiometry. Thus, single-layer Fe segregation occurred in Fe-rich samples while, in Al-rich alloys, complex multilayer Al segregation occurred; with the possibility of grain-boundary phase transitions. A grain-boundary glide which was weakly dependent upon grain-boundary chemistry seemed to be possible in the [001] direction. These features were suggested to contribute to the marked dependence, upon the bulk composition, of the mechanical properties of this material.

Influence of Bulk Composition on Grain Boundary Segregation in B2 Fe-Al - an Atomic-Scale Simulation Study. R.Besson, A.Legris, J.Morillo: Physical Review B, 2001, 64[17], 174105 (14pp)