Synthesis and characterization of Zr-based in situ crystal precipitated and liquid phase separated bulk metallic glass composite

The aim of this study was to evaluate new Zr-based bulk metallic composites with crystallized dendrites or droplets which have the volume fraction below the critical one (the percolation limit). The Cu36Zr48Al8Ag8 alloy was chosen as matrix. Dendrites formed by in-situ solidification due to Ni addition. It was found that a new monotectic alloy system can be created successfully owing to Y addition (1-7 at.%) to the matrix. Small amount of dendrites with non-random distribution has a strong influence on the compressive strength. Experiment showed that the alloy with 4.1 at.% Ni has the maximum compressive strength (1998 MPa) and Young's modulus (86 GPa) within the examined samples. The results of compression test reveal that the cracks propagate near the small droplets below 1 μm in diameter which generate weakening in the microstructure. In contrast, the large droplets especially above 3 μm in diameter create a strong barrier for the shear band propagation.