Theoretical and experimental studies of devitrification pathways in the Zr2Cu1−xPdx metallic glass system

✍ Scribed by J.R. Morris; Min Xu; Y.Y. Ye; D.J. Sordelet; M.J. Kramer

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 877 KB
• Volume: 55
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2007.07.021

✦ Synopsis

Using a model amorphous alloy series, Zr 2 Cu 1Àx Pd x (x = 0, 0.25, 0.5, 0.75 and 1), we demonstrate that ab initio calculations can predict likely metastable phase formation during devitrification by comparing these with time-resolved X-ray scattering studies. All compositions share the same equilibrium C11 b phase, yet they follow different devitrification pathways. Only x = 0.5 leads to a metastable C16 phase formation. This corresponds precisely to calculations showing the C16 phase is closest in energy to the stable C11 b phase. The competition is shown to be dominated by electronic structure rather than size effects, with the favored composition for the C16 phase forming a pseudo-gap at the Fermi energy. All Pd-containing compounds devitrify first into a quasicrystalline phase. Zr 2 Cu 1Àx Pd x compounds based on the NiTi 2 O 5 h structure are higher in energy relative to the C16 and C11 b structures for all compositions, and the calculations show no increase in stability with Pd concentration.