Phase Separation in Ce-Based Metallic Glasses

In this chapter, the results of our recent studies on the role of Ga substitution in place of Al in Ce75Al25 − xGax (x = 0, 0.01, 0.1, 0.5, 1, 2, 4, and 6) metallic glasses (MGs) have been discussed with the aim to understand the genesis of phase separation. X-ray diffraction (XRD) study reveals two broad diffuse peaks corresponding to the coexistence of two amorphous phases. In order to see any change in the behavior of 4f electron of Ce, X-ray absorption spectroscopy (XAS) has been carried out for Ce75Al25 − xGax MGs. From the XAS results, it is evident that for x = 0, the spectrum exhibits only a 4f1 component, which basically shows a pure localized configuration of electron. After the addition of Ga, 4f electrons of Ce atoms denoted by 4f0 are getting delocalized. Thus, the phase separation in Ce75Al25 − xGax is taking place, owing to the formation of two types of amorphous phases having localized and delocalized 4f electrons of Ce atoms, respectively. It has been discussed how change in the electronic structure of Ce atoms may lead to phase separation in Ce75Al25 − xGax alloys. Extensive TEM investigations have been done to study the phase separation in these alloys. The microstructural features have been compared with those obtained by phase field modeling.