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

The high‐temperature structure of the Σ = 5 bicrystalline interface of B2 NiAl with a large boundary plane is investigated by molecular dynamics simulations on parallel computers. It is observed that the atoms in the grain boundary region tend to form clusters in a thermal structural disorder transition, which is initiated at a temperature well below the thermodynamic melting point T m (∼0.52 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 temperature. When the temperature is up to T m , the abrupt growth of the clusters induces melting. Once above T m , the number and size of the clusters decrease significantly upon raising the temperature. The calculations of the potential energy also indicate that the thermal disorder transition is a continuous process, in contrast to the first‐order melting transformation. Copyright © 2001 John Wiley & Sons, Ltd.