Ion-beam-induced metastable phases in the Au–Co system

Abstract
Supersaturated Au–Co solid solutions have been obtained by ion-beam mixing of thin deposited Au and Co layers of compositions Au75Co25, Au50Co50, Au25Co75 and Au5Co95. X-ray diffraction measurements showed that the metastable alloys resulting from room-temperature ion implantation had a f.c.c. structure and that the lattice parameters of the alloys varied almost linearly with the composition. The structure of the alloys produced by low (LN2) temperature implantation was found to be more random in nature. An amorphous phase was obtained for the alloy with a composition Au25Co75. The microstructures of the ion-induced alloys were studied by transmission electron microscopy and their stability was examined by thermal annealing up to 500°C. The present results are compared with those obtained previously by splat-cooling and vapour-deposition techniques.