Effects of B and S on Ni3Al Grain Boundaries
In many materials, the mechanical behavior is controlled by the grain boundary (GB) properties. An extreme example is the ordered alloy Ni3Al, which, as a single crystal, is ductile, while as a pure polycrystal, exhibits severe intergranular brittleness, making it useless as a technological material. However, it has been found  that doping Ni3Al that is slightly Ni-rich (76% Ni) with small amounts of boron (~l-2 atomic %) restores the ductility almost to the level of the single crystal. While it is known experimentally that B segregates to grain boundaries , the mechanism by which ductilization occurs is not known. We present here results of our initial investigation into the effects of impurities on Ni3Al grain boundaries, using interatomic potentials of the embedded atom [2,3] form, coupled with molecular statics techniques.
KeywordsGrain Boundary Interatomic Potential Embed Atom Method Symmetric Tilt Octahedral Interstitial Site
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- 4.“Grain Boundary Structure and Kinetics”, ed. by R.W. Balluffi, ASM, Metals Park, OH (1980).Google Scholar
- 5.A.P. Sutton, Int. Metals Rev. 29:377 (1984).Google Scholar
- 11.J.A. Nelder and R. Mead, Comp J. 7:308 (1965).Google Scholar
- 13.J. Douin, P. Veyssière, and P. Beauchamp, Phil. Mag. A54:375 (1986).Google Scholar
- 18.V. Vitek, S.P. Chen, A.F. Voter, J.J. Kruisman, and J.Th.M. DeHosson, in: “Grain Boundary Chemistry and Intergranular Fracture”, G.S. Was, ed., Trans. Tech. Publications (1989).Google Scholar
- 20.S.P. Chen, A.F. Voter, R.C. Albers, A.M. Boring, and P.J. Hay, J. Mater. Res., submitted.Google Scholar
- 21.“Embrittlement of Engineering Alloys”, C.L. Briant and S.K. Banerji, eds. Academic Press, New York, NY (1983).Google Scholar