Composites of amorphous and nanocrystalline Zr–Cu–Al–Nb bulk materials synthesized by spark plasma sintering

The fabrication of Zr₇₀Cu₂₄Al₄Nb₂ bulk metallic glass composite samples by spark plasma sintering (SPS) process has been successfully realized. The unique characteristics of bulk metallic glasses could lead to the possibility of future applications as new structural and functional materials. The densification of an amorphous Zr₇₀Cu₂₄Al₄Nb₂ powder was realized in a systematic study changing the sintering temperature in the SPS process leading to stable composites characteristic of amorphous and nanocrystalline structures. X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) analysis, transmission electron microscopy (TEM) as well as hardness tests were applied to determine the structural and mechanical properties of the sintered materials. A stable amorphous bulk metallic glass based on Zr₇₀Cu₂₄Al₄Nb₂ with a low fraction of crystallites could be fabricated applying a nominal sintering temperature of 400 °C. Higher sintering temperatures lead to composites with high fractions of nanocrystalline material with porosities below 0.5%.