Change in atomic coordination in a heavily deformed metallic glass

The local structure around Ni and La atoms in Al85Ni10La5 amorphous powder after ball milling was investigated by X ray absorption spectroscopy. A continuous decrease in coordination number of Ni and La as a function of milling time was observed, while the nearest neighbour distance and the mean square atomic displacement did not change, pointing at the creation of free volume around the Ni and La atoms. These structural changes resemble those of a liquid upon temperature increase. The results are described by a shear band model in which the coordination numbers of Ni and La are different within and outside a shear ban