Preparation, microstructure and mechanical properties of carbon fiber containing bulk metallic glass composites

In monolithic form Zr-based bulk metallic glasses (BMG) e xhibit excellent strength and fracture toughness, but under uniaxial loading they fail catastrophically on one dominant shear band without showing significant macroscopic plasticity. In this investigation a composite approach is used in order to manipulate the nucleation and stability of shear bands in a BMG. We prepared carbon fiber containing composites using the Zr-Ti-Cu-Ni-Be bulk metallic glass forming system as a matrix. Investigations of the glass forming ability in presence of carbon phases show no heterogeneous nucleation at the carbon/BMG interface. Different types of composites with graphite or amorphous carbon fibers were prepared and the resulting microstructures were analyzed by x-ray diffraction, microprobe analysis, scanning and transmission electron microscopy. In the case of graphite fiber reinforcement a good processability was observed due to the reactive wetting behavior between carbon and the melt. The mechanical properties of the composites were characterized by hardness measurements and compressive testing. Also, the fracture mode and features of the fracture surface were analyzed.