Nanometer-scale phase separation in Al60Ge30Mn10 amorphous alloy

Nanometer-scale phase separation has been explored in an Al60Ge30Mn10 amorphous alloy, where all atomic pairs have negative heats of mixing. Here we use a combination of experimental (X-ray diffraction, X-ray absorption fine structure, small angle X-ray scattering and transmission electron microscopy) and simulation (Ab initio molecular dynamics and reverse Monte Carlo) techniques to resolve the atomic- and micrometer-level structures in the phase-separated Al60Ge30Mn10 amorphous alloy. Three characteristic peaks appear in the structure factor, linking with three kinds of composition fluctuation regions with different heterogeneous structures. The origin of three characteristic peaks is investigated in details and attributed to different atomic pairs. By analyzing the local chemical ordering between main polyhedra, we find that various phases exhibit differences in atomic structure, composition and bond-orientational order. The results obtained here provide atomic-scale understanding of the nanometer-scale phase separation phenomenon in Al60Ge30Mn10 amorphous alloy.