A parallel, computer simulation and high-resolution electron microscopic, study was made of the atomic structure of the Σ = 5 (210) θ = 53.13˚ and (310) θ = 36.87˚ [001] tilt axis grain boundaries in body-centered cubic material. The excess energy values of various boundary configurations were deduced from a quasi-dynamic minimization scheme, while cohesion was described by using a new n-body central-force phenomenological potential which satisfactorily reproduced static and dynamic properties of the bulk material. High-resolution electron microscopic observations and numerical modelling both revealed that the symmetrical configuration of the Σ = 5 (210) θ = 53.13˚ boundary had the lowest energy. The calculations also showed that the stable Σ = 5 (310) θ = 36.87˚ configuration was almost mirror-symmetrical; although experimental verification was incomplete. After a few oscillations, the interplanar spacing near to the boundaries converged rapidly to its bulk value while producing an overall expansion of the bi-crystal. Qualitative agreement was found between the calculated and experimentally determined expansion values. These results contradicted previous conclusions to the effect that phenomenological n-body central-force potentials would not be able to provide a satisfactory description of a grain-boundary structure in body-centered cubic transition metal.

Atomic Structure of the Σ = 5, (210) and (310), [001] Tilt Axis Grain Boundaries in Mo M.Bacia, J.Morillo, J.M.Pénisson, V.Pontikis: Philosophical Magazine A, 1997, 76[5], 945-63