Glass formation in the Nb–Si binary system

Nb81.3Si18.7 ribbons were prepared by rapid quenching of the liquid on a rotating copper wheel using various values of rotating speed. It was found that the melt spun ribbons consisted of an amorphous matrix; however the critical cooling rate for the formation of fully amorphous ribbons was achieved at rather high values of wheel speed. Crystallization occurs upon annealing above 971 K. The Vickers hardness of the amorphous ribbons was found to be 915 HV, an unusually high value for a binary alloy. The atomic structure of the amorphous Nb–Si alloy was studied using real space pair distribution (PDF)/radial distribution functions (RDF) derived from high precision X-ray diffraction data acquired with high-energy, monochromatic synchrotron light in transmission.