A parallel computer simulation and high-resolution electron microscopic study was made of the atomic structure of the S = 5 (210)[001] symmetrical tilt grain boundary in body-centered cubic Mo. The excess energy values of various boundary configurations were deduced by using a quasi-dynamic minimization scheme, while cohesion was described by a new n-body central-force phenomenological potential which reproduced the static and dynamic properties of the bulk material. High-resolution electron microscopic observations and numerical modelling both showed that the symmetrical configuration of the S = 5 (210)[001] tilt grain boundary had the lowest energy. A previously published simulation study had predicted non-symmetrical configurations for the same grain boundary, regardless of the cohesion model which was used. It was unclear why the present implementation of a central-force potential for Mo consistently reproduced experimental observations. However, it was pointed out that it differed from other published models in that it satisfactorily reproduced a large number of bulk thermodynamic properties. Also, it worked well with regard to the grain boundary but its predictions for surfaces were poor. It was proposed that any cohesive model must above all behave correctly with regard to bulk properties rather than surface properties, in order to describe grain boundaries properly in a body-centered cubic metal like Mo.

Computer Simulation and High-Resolution Electron Microscopy Study of the S = 5 (210) [001] Symmetrical Tilt Grain Boundary in Molybdenum. M.Bacia, J.Morillo, J.M.Pénisson, V.Pontikis: Materials Science Forum, 1999, 294-296, 203-6