Microstructure and mechanical properties of Zr-Ti-Cu-Nd metallic glass composites

Different amounts of Nd were added to fabricate Zr-Ti-Cu-Nd metallic glass ribbons using melt-spinning and both the microstructure and mechanical properties were examined. Because of the different mixing enthalpies between elements, liquid-phase-separation occurs during the cooling process. While Nd separated from Zr and Ti, it precipitated with Cu. This was verified using energy-dispersive X-ray spectroscopy. Also, the cooling rate varies through the thickness of the ribbon during melt spinning which, in turn, would result in different microstructures. While the ribbon was fully amorphous on the roller side, it had fine and coarse precipitates, respectively, on the surface side and in the middle thickness of the ribbon. Using modulus mapping, the matrix showed the higher storage modulus than the precipitates while the precipitates had the higher loss modulus. The micropillar compression tests showed the enhanced ductility of the ribbon with Nd doping, and the micrographs showed abundant shear bands and shear-cutting of precipitates by the shear band after compression.