Atom probe studies of metallic glasses

Atom probe tomography was used to characterize the distribution of atoms in bulk amorphous Pd40Ni40P20, Pd40Ni40-xFexP20 (0 < x < 20), and (Pd50Cu50)(100-x)P-x (x = 16.5, 17.5, 19) alloys. The analyses were performed on samples cut from 7-mm diameter rods, which were prepared by quenching the melt at cooling rates of approximately 200 K/s. All the alloys were examined in the as-quenched condition. In the Pd40Ni40-xFexP20 glasses, the increase in Fe concentration causes a systematic increase in the clustering of palladium and ordering of phosphorus. The 20% Fe alloy exhibited a two-phase microstructure. The (Pd50Cu50)(100-x)P-x glasses exhibited fine-scale phase separation into copper-enriched/phosphorus-depleted and copper-depleted/phosphorus-enriched regions. These observations follow from statistical analysis of the concentration frequency distributions, the composition enrichments of shells around each atom, and composition maps. (C) 2003 Elsevier Science B.V. All rights reserved.