The complex stoichiometry of ternary alloys: What lies beyond the canonical Bernoulli distribution?

Structural properties of ternary alloys (C1−xC′x)Im depend on relative configuration probabilities that change with the relative content x. Relative configuration probabilities depend on the intensity of site occupation preferences. Several ternary systems show ideal quasi-canonical Bernoulli distributions of their configuration, while others are characterized by extreme preferences in which one, several or even all configurations are depressed or even lacking. In cases with extreme preferences, only two binary configurations (CIm and C′Im) occur, with no ternary configuration formed. We discuss here in a statistical framework the site occupation preferences of 16 ternary alloys with B3, B4, L12 and C15 crystallographic structures pointing out the observed deviations from the ideal Bernoulli distribution.