Phase separation in bulk-type Gd–Zr–Al–Ni metallic glass

Phase separation in bulk-type metallic glass and effect of cooling rate on the phase-separated microstructure have been investigated in Zr35Gd20Al25−xNi20+x (x = 0, 2, 4, 8) alloys. Among the alloys investigated, molten Zr35Gd20Al23Ni22 undergoes metastable liquid phase separation in the undercooled regime and subsequently solidifies into two different Zr-rich and Gd-rich amorphous phases, which exhibit enough GFA enabling formation of 1 mm diameter phase-separating glass. The liquid melt undergoes phase separation by spinodal decomposition when the degree of undercooling is relatively large, while by nucleation and growth mechanism when the degree of undercooling is relatively low. The lower degree of undercooling results in the composition more close to the terminal composition expected from the miscibility gap.