Formation of a phase separating bulk metallic glass in Cu40Zr40Al10Ag10 alloy

The Cu40Zr40Al10Ag10 glassy alloy prepared by different methods was investigated using X-ray diffraction, differential scanning calorimetry and transmission electron microscopy. The bulk sample prepared by copper mold casting exhibits the same XRD pattern and DSC scan as the ribbon sample prepared by melt spinning. TEM shows a homogenous and non-contrast pattern for the Cu40Zr40Al10Ag10 ribbon sample. However, it was found that the bulk sample consisted of worm-like phases with a dark contrast homogeneously embedded in a matrix with a light contrast. The TEM and EDS results show that the dark and light contrast phases are completely amorphous, and the dark-contrast phase has high Ag and lower Cu contents, indicating the phase separation occurs in the as-cast Cu40Zr40Al10Ag10 BMG.