Molecular dynamics study for structural stability of the interface at elevated temperatures

The high-temperature structure of the Sigma = 5 bicrystalline interface of B2 NiAl with a large boundary plane is investigated by molecular dynamics s imulations on parallel computers. It is observed that the atoms in the grai n boundary region tend to form clusters in a thermal structural disorder tr ansition, which is initiated at a temperature well below the thermodynamic melting point T-m (similar to0.52 T-m). The number and size of the clusters are monitored over a wide temperature range including T-m. Below T-m, the number and size of the clusters increase continuously with increasing tempe rature. When the temperature is up to T-m, the abrupt growth of the cluster s induces melting. Once above Tm, the number and size of the clusters decre ase significantly upon raising the temperature. The calculations of the pot ential energy also indicate that the thermal disorder transition is a conti nuous process, in contrast to the first-order melting transformation. Copyr ight (C) 2001 John Wiley & Sons, Ltd.