In situ formation of two amorphous phases by liquid phase separation in Y–Ti–Al–Co alloy

The $Y28Ti28Al24Co20$ alloy undergoes metastable liquid phase separation in the under-cooled liquid state and subsequently solidifies into two different Y-rich and Ti-rich amorphous phases. Secondary phase separation occurs due to the supersaturation of the primary separated liquids as the temperature decreases. Depending on the degree of local undercooling, a wide range of length scale of the microstructure is observed. The characteristic length scale of the two amorphous phases is $∼250nm$ near the air side of the ribbon, and $∼25nm$ near the wheel side of the ribbon.