First Principles Investigation of the Ir-Zr-Nb Ternary System

Alloy design could benefit greatly from a systematic approach that combines current empirical practices with the predictive capabilities of computer modeling such as first principles based methods. At this point in time, realization of such an aid to alloy design requires the investigation of alloying systems based on first principles approaches to determine ultimate limitations and gauge the merits of this type of predictive method. The following study begins an investigation of the Ir-Zr-Nb ternary system based on combining first principles total energy calculations with a statistical mechanics description of solids. The Ir-Zr-Nb ternary system was initially chosen for the two highly ordered binary systems, Ir-Zr and Ir-Nb, and, more specifically, for coordinating with experimental work on the Ir3Zr1-xNbx system. The two main contributions of this study include compiling a database of first principles data for fcc- and bcc-based compounds for the Ir-Zr-Nb ternary system, and calculating the Ir-Zr-Nb fcc metastable ternary phase diagram.