The multiplicity of possible grain boundary structures was studied for the ordered compound Ni3Al. Two symmetrical tilt boundaries were chosen for the detailed study corresponding to ∑=3 <110>{012} and ∑=9 <110>{114}. These boundaries were investigated considering possible variations of the local chemical composition as well as the surrounding matrix using atomistic computer simulations with EAM interatomic potentials. Many different grain boundary structures were found to have very similar energies for the same orientation of the two crystals and the grain boundary plane. The possible transformations among these structures that may result from the interaction of the boundaries with dislocations or antiphase boundaries were studied, including the energetics of the junctions between the different structures. The role of the multiplicity of structures and these transformations in the grain boundary mechanical properties was discussed and a model was proposed for the tendency to grain boundary brittleness observed in Ni3Al.

The Multiplicity of Possible Grain Boundary Structures in Ni3Al. Farkas, D., Cardozo, F.A.: Intermetallics, 1998, 6[4], 257-68