Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1626946 | Journal of Alloys and Compounds | 2006 | 9 Pages |
It is shown here that crystallographic descriptions of hypothetical AB63, AB107, AB127, AB215 and especially AB255 stoichiometric compounds with cell edge, respectively 4, 3, 4, 6 and four times the (A,B) fcc subcell edge stick out as convenient models for ab initio studies of cell data versus composition for ccp solid-solution alloys. Their Wyckoff positions can be combined to generate most binary alloy compositions from 0% to 100% in multiples of 1/64, 1/108, 1/128, 1/216 and 1/256 while retaining the same periodicity and, respectively the same Fm 3¯m, Pm 3¯m, Im 3¯m, Fm 3¯m and Pm 3¯m space group symmetry. As an application, we model cell data for three cubic solid-solution alloys of Pt. (Pt,Ir) and (Pt,Ru) remain close to Vegard's law predictions with a slight convexity or concavity in the plot. That curvature is explainable by the magnitude and sign of the alloying energy. Modeling of (Pt,Re) between 0% and 45% Re in 50 steps of RenPt108−n stoichiometric compounds follows approximately non-Vegard experimental data but with large, unexplained spread. The method has been automated in Materials Toolkit (http://www.tothcanada.com/toolkit).