Calculation of the Griffith Cohesive Energy of theNi3AlBx Symmetrical Grain Boundary

Abstract

A Monte Carlo simulation, with the energetics described by the embeddedatom method, has been employed to study the physical behaviour of boron atomsduring relaxation of the Ni3AlBx grain boundary. It has also been usedto calculate not only the peak concentrations of Ni and B and the valleyconcentration of Al at the grain boundary, but also the dependence of thegrain boundary cohesion on the B bulk concentration. During relaxationof impure Ni3Al grain boundaries, we suggest that, as thesegregating species, the B atoms either insert into interstices in thegrain boundary or substitute Ni atoms. Meanwhile, as the inducingspecies, they induce Ni atoms to substitute for Al atoms. Calculationsshow that in the equilibrium, when the B bulk concentration xincreases from 0.1 to 0.9, the peak concentration of B increases, thepeak concentration of Ni maximizes while the valley concentration of Alminimizes at x = 0.5. The calculations also show the best cohesion of thegrain boundary at x = 0.5.