Atomistic simulation of grain boundary energetics - Effects of dopants

Many enhancements in properties of nanocrystalline materials due to the ultra-fine grain size are lost if grain growth occurs during application. As a preliminary study, molecular statics (MS) and molecular dynamics (MD) simulations are used to study the energy of a two-dimensional coincident site lattice (sigma)7 symmetric tilt grain boundary in a Cu bicrystal. Impurity atom(s) of various characteristics and concentration were added to the near vicinity of the grain boundary to determine the structural and energetic affect. The dopant atoms are capable of altering the grain boundary energy even if several atomic spacings separate the two. Also, it is shown that the grain boundary energy can be reduced to zero, which has been theoretically proposed as necessary for achieving a metastable state for nanocrystals. The results of this investigation will aid further computational and experimental work aimed at stabilizing the microstructure of nanocrystalline material.