| Popis: |
Fracture behavior of Zr-based bulk metallic glasses (BMG) and metallic glass matrix composites (BMGMC), was investigated while varying testing temperature, loading condition and strain rate. Samples were tested in tension, compression, three-point bending and Charpy impact in order to determine the effects of changes in strain rate and test temperature on the tensile strength, compressive strength, ductility, fracture toughness and impact toughness. An increase in temperature was found to have a similar effect as decreasing strain rate. At similar temperatures, displacement-controlled tensile tests caused severe necking to failure after significant ductility, while load-controlled conditions caused samples to draw into long, thin wires, a morphology that was not observed in BMGMC samples. Microstructural evolution of dendrites in deformed BMGMC samples was characterized using electron backscatter diffraction (EBSD) to determine change in crystallographic orientation with progressing deformation. Less dendrite area was indexable as deformation progressed, and the operative deformation mechanism was theorized to be dislocation motion. |
