Is Cu60Ti10Zr30 a bulk glass-forming alloy?

The microstructures of Cu60Ti10Zr30 alloys fabricated by using two different methods, (rods of 2.5 mm in diameter prepared by a copper-mold casting method, and ribbons of about 0.03 mm in thickness prepared by the melt-spinning method), have been investigated by transmission electron microscopy and high-resolution transmission electron microscopy. Surprisingly, we found that the alloy in both geometries contains cubic nanometer-sized crystals of about 5-7 nm in diameter with a lattice parameter of 0.45 nm for ribbons and 7-15 nm in diameter with a lattice parameter of 0.42 nm for rods. Nanocrystals with a significant volume fraction are randomly distributed in the amorphous matrix. The copper element is enriched in nanocrystals while a slightly high zirconium content is found in the matrix. We classify that the Cu60Ti10Zr30 alloy prepared by both of the aforementioned methods is a nanocomposite: Nanocrystals embedded in an amorphous matrix.