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

Abstract

Cu–Co alloys of bulk compositions Cu75Co25 and Cu84Co16 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 Cu75Co25 sample than for the Cu84Co16 sample, whilst the composition distribution of the droplets is broader in the Cu75Co25 sample than in the Cu84Co16 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.