Abstract
Thermal disordering and melting at a grain boundary are investigated by molecular dynamics in an internally consistent simulation model that avoids a number of pitfalls of earlier models. The bulk melting temperature of the model system, specified by an embedded-atom-method potential function fitted to aluminum, is first determined by observing directly surface-nucleated melting in a single-crystal cell with free surfaces. Simulation is then carried out on a bicrystal cell with a high-angle symmetrical tilt grain boundary on the (1¯30) plane. Profiles across the interface of local structural order and energy, along with data on atomic mobility, are obtained at several temperatures from below to above ; the results indicate that melting is nucleated at the grain boundary in a similar manner as at the free surface, and that there is no evidence of premelting. In the surface region as well as the grain-boundary core, thermal disordering at temperatures below was observed with characteristic metastable behavior commencing at about 0.93 . The temperature variation of the interfacial thickness suggests that the onset of disordering is a continuous process.
- Received 12 December 1991
DOI:https://doi.org/10.1103/PhysRevB.46.6050
©1992 American Physical Society