The local atomic structure of ${\mathrm{Al}}_{87}{\mathrm{Ni}}_7{\mathrm{Nd}}_6$ amorphous metallic glass was determined by neutron diffraction and the pair density function (PDF) analysis. The local environments of the transition metal and rare earth ions were separately determined using $\mathrm{Ni}$ (${}^{58}\mathrm{Ni}$ and ${}^{60}\mathrm{Ni}$) and $\mathrm{Nd}$ (${}^{142}\mathrm{Nd}$ and ${}^{144}\mathrm{Nd}$) isotopes with very different neutron scattering lengths to separate their contributions. A distinct pre-peak was observed in reciprocal space indicative of clustering, a feature commonly present in good glass forming systems. The intensity of the pre-peak changes significantly with the substitution of $\mathrm{Ni}$ isotope but not so with $\mathrm{Nd}$, suggesting that the transition metal is a major component to this peak. Such clustering might be a manifestation of chemical short-range ordering that is enhanced with $\mathrm{Ni}$. The local environments for the $\mathrm{Ni}$ and $\mathrm{Nd}$ ions determined by the isotope difference PDF analysis are fundamentally distinct because $\mathrm{Ni}$ and $\mathrm{Nd}$ interact differently with $\mathrm{Al}$ giving rise to unique topologies. In particular for $\mathrm{Ni}$, $\mathrm{Ni}\text{−}\mathrm{Al}$ bond lengths are anomalously short due to stronger $\mathrm{Ni}\text{−}\mathrm{Al}$ interactions and the local environment consists of distinct pair correlations. In contrast, the local $\mathrm{Nd}$ environment is more disordered with two separate $\mathrm{Nd}\text{−}\mathrm{Al}$ environments and possibly relatively weaker interactions.

• Received 3 October 2003

DOI:https://doi.org/10.1103/PhysRevB.70.224103