Bulk Metallic Glasses
… a revolution in metallurgy
Advancements in materials research are the key to future technological development. Since 2005, the Chair of Metallic Materials (LMW) has laid the foundations for innovation in the field of Bulk Metallic Glasses.
What are Bulk Metallic Glasses?
Bulk Metallic Glasses (BMGs) are multicomponent metallic alloys with liquidus temperatures far below the melting points of the main constituent elements. BMG forming alloys are characterized by their extremely low tendency to crystallize into a periodic atomic lattice that is associated with a volume change. Instead, these alloys form a glass with a macroscopically disordered structure. This amorphous structure gives BMGs unique properties, making these alloys particularly interesting for a range of technological applications.
Metallic glasses are characterized by their superior mechanical properties. Their high strength (approx. 2 GPa) together with their high maximum elastic strains (approx. 2 %) and low damping make BMGs ideal spring materials.
Their high corrosion resistance makes amorphous metals particularly interesting for coatings and components that are subjected to adverse environmental conditions.
There are innumerable varied manufacturing processes for components made from metallic glass. Because BMGs exhibit significantly less shrinkage upon cooling, they can be processed in manners that are otherwise impossible for conventional crystalline alloys. Possibilities include classical casting methods from metals processing as well as injection molding, thermoplastic forming, and rapid prototyping techniques that are typically only viable for polymer materials. Furthermore, the near-net shape formability of BMGs permits the manufacture of components that require little to no additional post-production finishing steps.
The greatest challenge of producing BMG components lies in increasing the maximum thickness that can be solidified in the glassy state. As a result of the ongoing research in the field of metallic glasses, modern BMG components can be produced with dimensions up to several centimeters.
Fields of Research
The research interests at the Chair of Metallic Materials can be divided into three subjects:
- The LMW conducts basic research into the thermodynamics and kinetics of metallic glasses. One of the central research interests focuses on the relationship between the structure and the macroscopic properties (e.g. Viscosity) of BMGs. To achieve this, the LMW regularly collaborates with major research facilities, including the German Aerospace Center (DLR), German Electron-Synchrotron (DESY), and the European Synchrotron Radiation Facility (ESRF).
- The LMW is also committed to the development of new and innovative BMG alloys. With the help of thermal analysis in the specialized laboratories at the LMW, continuous advancement of the glass forming ability of these alloys is made possible. The primary goal of these investigations is the creation of commercially viable structural materials for small components.
- The third research subject focuses on the processing technology used to manufacture amorphous and crystalline feedstock from BMG-forming alloys as well as the near-net-shape production of amorphous components with various methods. One of the principal themes here is the upscaling of laboratory processes to accommodate the demands of industrial production.