Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1450921 | Acta Materialia | 2005 | 8 Pages |
Abstract
Grain boundary structure and grain boundary segregation in stoichiometric and Ni-rich compositions of NiAl are studied by molecular statics and grand-canonical Monte-Carlo simulations in conjunction with an embedded-atom potential. Significant Ni segregation is found at the Σ = 3(1 1 1) and Σ = 3(2 1 1) grain boundaries, with segregation isotherms showing a saturation effect. The amount of Ni segregation increases and the excess free energy of the grain boundaries decreases with increased Ni bulk concentration. In strongly Ni-rich bulk compositions, both boundaries undergo transformations to new structures capable of accommodating more excess Ni atoms than the initial structures. The structural transformation is clearly manifested by a non-monotonic behavior of the segregation isotherm. In the Σ = 3(2 1 1) grain boundary, the transformation is accompanied by a relative tangential translation of the grains.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
J.A. Brown, Y. Mishin,