Stress-corrosion and corrosion-fatigue of Zr-based bulk metallic glasses

Bulk metallic glasses show interesting mechanical properties under compressive loading conditions. Especially their high strength combined with large elastic deformation make them appropriate for various technical applications. However, because of their brittle fracture behavior, lack of plasticity and very high manufacturing costs, it has not yet been possible to establish bulk metallic glasses as structural materials in the industry. For gaining an intense understanding of their mechanical behavior, quasi-static and cyclic three-point bending tests in air and corrosive media under anodic/cathodic polarization are conducted in the framework of PP 1594. Crack propagation during cyclic testing is recorded in situ by electric resistivity (tests in air), respectively by microscope camera (tests in electrolyte), and crack propagation curves are developed by the resulting data. As the focus of the project is on stress-corrosion interactions, as well as the influence of chloride containing electrolyte and different applied electric potentials on fracture behavior, plasticity and crack growth are investigated. An increase in shear band formation by the absorption of hydrogen near the sample surface is suggested to enhance the plastic deformation capability of bulk metallic glasses. Furthermore, the influence of micro notches on fatigue properties will be investigated. The bending samples for mechanical and electrochemical testing are manufactured at Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW) Dresden. Finally, all results of the research will be used to develop a comprehensive model describing crack initiation and propagation mechanisms during corrosion-fatigue tests for Zr-based bulk metallic glasses.

Contact: Dipl.-Ing. Daniel Grell