Electronic stability of clusters in devitrification phases of Zr-based amorphous alloys

The discrete variational method is used to calculate the electronic structure of the clusters such as Zr9Ni4 and Zr10Cu5 in the primary devitrification phases such as fcc–Zr2Ni and bct–Zr2Cu in Zr-based amorphous alloys. In order to reveal the effect of Al on the stability of these clusters, Al atoms are introduced to replace Ni or Cu. The calculated density of states curves show that the Zr9Ni3Al cluster is more stable than Zr9Ni4 but the stability deteriorates with more Al substitutions. For the Zr10Cu5 cluster, one Al stabilizes this cluster but more Al substitutions destabilize it because more electrons are activated towards high energy levels. This stability mechanism explains the superior stability of the Zr–Al–Ni and Zr–Al–Cu amorphous alloys with respect to the binary Zr–Cu and Zr–Ni amorphous alloys.