Zr and Hf microalloying in an Al-Y-Fe amorphous alloy. Relation between local structure and glass-forming ability
A. Sadoc a; M. Sabra a; O. Proux bc; J. -L. Hazemann bd; K. S. Bondi e; K. F. Kelton e
a LPMS, Universit
de Cergy-Pontoise, Cergy-Pontoise Cedex, Franceb CRG-FAME beamline, ESRF, Grenoble Cedex, France
c Laboratoire de G
ophysique Interne et Tectonophysique, Saint-Martin-D'H
res, Franced Institut N
l, Grenoble Cedex 09, Francee Department of Physics, Washington University, St. Louis, MO 63130, USA
Abstract
The effects of the addition of small amounts of Zr and Hf (0.5-3%) on the atomic structure of Al88Y7Fe5 metallic glass were examined from extended X-ray absorption fine structure (EXAFS) experiments to better understand the influence of these microadditions on the glass-forming ability of this alloy. Measurements at the Zr K and Hf LIII absorption edges allowed the local structures around Zr and Hf atoms to be determined. The same Al environment was found for the different concentrations, consisting of a small cluster extending up to 4.5 
around the Zr atoms and up to 6 around the Hf ones. Although the clustering effect is smaller in the Zr neighbourhood, a drastic shortening of the nearest Zr-Al distance is shown, providing evidence for some covalent character to the bonding, in line with the increased glass-forming ability found in the alloys made with the Zr microaddition.
Keywords: nanostructure; metallic glasses; microalloying; Al-Y-Fe; EXAFS; glass-forming ability
around the Zr atoms and up to 6 around the Hf ones. Although the clustering effect is smaller in the Zr neighbourhood, a drastic shortening of the nearest Zr-Al distance is shown, providing evidence for some covalent character to the bonding, in line with the increased glass-forming ability found in the alloys made with the Zr microaddition.Keywords: nanostructure; metallic glasses; microalloying; Al-Y-Fe; EXAFS; glass-forming ability