A study of phase separated Ni66Nb17Y17 metallic glass using atom probe tomography

Microstructural characterization of Ni66Nb17Y17 as spun metallic glass ribbon was carried out using atom probe tomography. A comparison of different experimental conditions for pulsed laser and pulsed voltage field evaporation reveal that the laser pulsing can be optimized to avoid preferential evaporation of yttrium. Atom probe tomography measurements illustrate that the sample undergoes phase separation resulting in two interconnected phases during the process of vitrification. The yttrium-enriched phase was depleted in niobium and yttrium-depleted phase was enriched in niobium. Moreover, detailed analyses of the roller-contact and non-contact sides of the melt-spun ribbon show different wavelength of phase separated regions revealing that the degree of phase separation is directly associated with the cooling rate.