Dependence of Ni, Al and B boundary concentrations on the B bulk concentration for the Ni3Al-x at.% B grain boundary

We have applied the embedded atom method (EAM). to calculate boundary conce ntration distributions of Ni, Al and B, and B probabilities in the "interst itial" and, the "substitutional" sites, at the Ni3Al-x at.% B (100% Ni\100% Ni) [001]/Sigma5(210)/36.87 degrees. grain boundary at the equilibrium. We propose that the bulk effects of B on the grain boundary include the posit ive effect on the Ni enrichment at the grain boundary, i.e. the B atoms ind uce Ni atoms to substitute into Al sites, the negative effect on it, i.e. t he B atoms substitute into Ni sites, and the neutral effect on it, i.e. the B atoms insert into interstices in the grain boundary. Our calculations sh ow that owing to combination of the positive effect and the negative effect , corresponding to B-enrichment increasing, the Ni-enrichment and the Al-de pletion become more and more obvious, when x increases from 0.1 to 0.5. The n, corresponding to B-enrichment decreasing, the Ni-enrichment and the Al-d epletion also become more and more obvious, when x decreases from 0.9 to 0. 5. Thus, between low (x = 0.1) and high (x = 0.9) B bulk concentrations, th ere is a B bulk concentration (x = 0.5), at which the Ni-enrichment and the Al-depletion become the most obvious, even if Ni is approximately saturate d. (C) 2001 Elsevier Science B.V. All rights reserved.