Incoherent Σ3 Grain Boundaries in F.C.C. Metals : The Influence of Inclination on the Boundary Structure and Energy

The "Embedded Atom Method" (EAM) is used to study the energy and structure of different Σ3 grain boundaries defined by the inclination angle Φ. The grain boundary energy, γb, varies with Φ, i.e. the boundary plane orientation. For copper the γb (Φ) plot shows a deep energy minimum for the coherent (111) twin boundary for inclinations around the [01(-1)] axis. A second significant energy minimum is found ∼8° away from the incoherent ((-2)11) twin plane. The location of a minimum energy configuration near ((-2)11) is in good agreement with published experimental results. The structures of the inclined Σ3 incoherent boundaries of the cusp region show rigid body translations which are distributed over several lattice planes parallel to the interface and limited to one grain. The structures will be discussed and compared with observations on Au Σ3 incoherent twins.