Nanometer-scale solute clustering in aluminum–nickel–ytterbium metallic glasses

The transformation sequence of melt-spun Al–5.2at.% Ni–6.8at.% Yb is characterized by X-ray diffraction, differential scanning calorimetry (DSC), and atom-probe field-ion microscopy. An isochronal DSC thermogram detects three major exothermic transformation steps, with onset temperatures of 180, 292, and 327 °C, respectively. Atom-probe analyses reveal the evolution of compositional inhomogeneities on an atomic scale. In addition to Ni–clusters present in the as-quenched alloy, Ni–Yb co-clusters form during isochronal heating to 188 °C. Al–rich precipitates are detected after heating to 250 °C, with the Ni and Ni–Yb clusters still present, constituting possible precursors of intermetallic phases formed during advanced transformation stages.