材料期刊网

The embedded atom method (EAM) has been used to calculate boundary concentration distributions of Ni, Al, and B, and B probabilities in the "interstitial" and the "substitutional" sites, at the Ni3Al-x at.% B (100% Ni/100% Ni) [001]/Sigma5(210)/36.87degrees grain boundary at the equilibrium. It has been proposed by us that the bulk effects of B on the grain boundary include the main effect, that is, the B atoms induce Ni atoms to substitute into Al sites, and the sub-effect, that is, the B atoms substitute into Ni sites. In this work, it is found that at as x increases from 0.1 to 1.0, the B probability in the "interstitial" sites decreases from 97.3% to 38.8%, while that in the "substitutional" sites increases from 2.7% to 61.2%. It is also found that owing to combination of the main effect and the sub-effect, corresponding to B enrichment increasing, the Ni enrichment and the Al depletion become more and more obvious when x increases from 0.1 to 0.5. Then, corresponding to B enrichment decreasing, the Ni enrichment and the Al depletion 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, there is a B bulk concentration (x = 0.5), at which the Ni enrichment and the Al depletion become the most obvious, and Ni is approximately saturated. (C) 2002 Elsevier Science B.V All rights reserved.