Published online by Cambridge University Press: 15 May 2002
The crystallization processes of Zr70Cu20Rh10 and Zr70Cu27.5Rh2.5 metallic glasses were studied. The initial precipitates are the mixture of an icosahedral quasicrystalline phase (I phase) and a face centered cubic Zr2Rh phase (fcc-Zr2Rh) for Zr70Cu20Rh10 alloy and that for the Zr70Cu27.5Rh2.5 alloy is a single I phase. Under optimum annealing conditions, the largest I phase particle size is 40 nm and 80 nm for Zr70Cu20Rh10 and Zr70Cu27.5Rh2.5, respectively. To explain these results, it is assumed that icosahedral atomic cluster exists in the metallic glasses, which serves as the seeds for the precipitation of metastable I and FCC-Zr2Rh phases. Further, it is suggested that the number density of icosahedral atomic cluster and the ease of fcc-Zr2Rh phase formation depend on the Rh concentration, which explain the above-mentioned dependence of the I phase particle size on Rh concentration.