An introduction to the BFS method and its use to model binary NiAl alloys
We introduce the Bozzolo–Ferrante–Smith (BFS) method for alloys as a computationally efficient tool for aiding in the process of alloy design. An intuitive description of the BFS method is provided, followed by a formal discussion of its implementation. The method is applied to the study of the defect structure of NiAl binary alloys. The groundwork is laid for a detailed progression to higher order NiAl-based alloys linking theoretical calculations and computer simulations based on the BFS method and experimental work validating each step of the alloy design process.
Embedded atom calculations of unstable stacking fault energies and surface energies in intermetallics
We performed embedded atom method calculations on surface energies and unstable stacking fault energies for a series of intermetallics for which interatomic potentials of the embedded atom type have recently been developed. These results were analyzed and applied to the prediction of relative ductility of these materials using the various current theories. Series of alloys with the B2 ordered structure were studied, and the results were compared to those in pure body-centered cubic (bcc) Fe. Ordered compounds with L1{sub 2} and L1{sub 0} structures based on the face-centered cubic (fcc) lattice were also studied. It was found that there is a correlation between the values of the antiphase boundary (APB) energies in B2 alloys and their unstackable stacking fault energies. Materials with higher APB energies tend to have higher unstable stacking fault energies, leading to an increased tendency to brittle fracture. {copyright} {ital 1997 Materials Research Society.}
Atomic rippling of a metallic ordered alloy surface--NiAl(110)
Results from a low‐energy electron diffraction (LEED) analysis of the NiAl(110) surface are presented and discussed. Ordered NiAl has a truncated bulk (110) surface consisting of composite layers of Ni and Al sites which are exactly coplanar. However, the present LEED results demonstrate that the actual NiAl(110) surface has a large rippled relaxation, with the Al sites of the outermost composite layer being 0.22 A above the Ni sites. The agreement achieved between the calculated and experimental I–V profiles, total R factor of 0.053, is of the same quality as that obtained in better LEED analyses of monatomic metallic surfaces, which indicates the evidence for the rippling is quite strong. Also, a qualitative plausibility argument is given to indicate that such rippling is to be expected in surfaces of ordered alloys.