Novel insight into microstructural evolution of phase-separated Cu-Co alloys under influence of forced convection

摘要

Cu-Co alloys of bulk compositions Cu_(75)Co_(25) and Cu_(84)Co_(16) were undercooled and solidified using electromagnetic levitation. Microstructure of the samples was characterized using optical microscopy, scanning electron microscopy, energy dispersive spectrometry, and micro X-ray diffraction analysis. It was found that besides a bimodal size distribution, droplets of the Co-rich L1 phase resulting from liquid phase separation have a broad composition distribution. The bimodal size distribution of the droplets is more pronounced for the Cu_(75)Co _(25) sample than for the Cu_(84)Co_(16) sample, whilst the composition distribution of the droplets is broader in the Cu _(75)Co_(25) sample than in the Cu_(84)Co_(16) sample. The droplets were found to also have different types of substructures in the two samples. The results provide novel insight into microstructural evolution of phase-separated alloys under influence of forced convection.