Theoretical Studies of Grain Boundaries in Ni, Al, and Ni 3 Al with and without Boron

Atomistic simulations of (001) symmetric tilt grain boundaries in Ni, Al, and Ni/sub 3/Al are presented. The atomistic structures of the simulated grain boundaries have been analyzed in terms of the structural unit model, which is found to be of limited utility for intermetallics. Simulation results show that boron segregates more strongly to grain boundaries than to free surfaces, and strengthens the grain boundary. Good cohesive properties of the grain boundaries occur when both boron and some segregated Ni are present. The Ni and B are found to co-segregate to the Ni/sub 3/Al boundary with an energy advantage of /approximately/0.5 eV. 17 refs., 3 figs.