Phase stability for the Cu-Zr system: First-principles, experiments and solution-based modeling

TitlePhase stability for the Cu-Zr system: First-principles, experiments and solution-based modeling
Publication TypeJournal Article
Year of Publication2010
AuthorsZhou SH, Napolitano RE
Journal TitleActa Materialia
Date Published04/01
ISBN Number1359-6454
Accession NumberISI:000275511700027
Keywordsamorphous-alloys, association, augmented-wave method, copper alloys, copper-zirconium alloys, GLASS-FORMATION, intermediate phases, intermetallic compounds, mechanical-properties, phase transformations, thermodynamics, transition-metals, x-ray-diffraction

First-principles calculations and experimental methods were employed to investigate the relative stability of intermetallic phases in the Cu-Zr system. Computed enthalpies of formation indicate that Cu51Zr14-beta and CuZr2-C11(b) are stable phases, while Cu-Zr-5-C15(b), Cu10Zr7-phi and CuZr-B2 are metastable at 0 K. Heat treatment and microanalysis revealed two important findings which clarify the phase equilibria. First, the stability range for the Cu5Zr-C15(b) phase was found to have a lower bound associated with an eutectoid invariant between 802 and 955 K, below which it decomposes to face-centered cubic Cu Plus Cu51Zr14-beta-Second, the Cu5Zr8 phase, previously reported as stable, was not observed in a Cu-56.4 at.% Zr alloy after holding at 955 and 1036 K for >100 h. This phase, therefore, was not considered to be stable. Based on computational and experimental results, Gibbs free energies were modeled, including the Cu2Zr-sigma, Cu24Zr13-mu and metastable CuZr-(B19' and B33) phases. The associated phase diagrams are presented. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

URL<Go to ISI>://000275511700027
DOIDoi 10.1016/J.Actamat.2009.12.004