Metallic glasses can be made in shapes ranging from thin films to ribbons to small ingots according to composition and processing technique, i. e. cooling rate. They are thermodynamically metastable and crystallize when heated above their crystallization temperature, Tx. Controlling this process allows in situ formation of crystalline-amorphous composites. Those which can be heated to above their glass transition temperature, Tg, but below Tx without crystallizing, can be molded similarly to thermoplastics because their viscosities drop considerably in the supercooled liquid region. This unique characteristic allows forming into small and intricate shapes applying to metals high-volume, low-cost, micro and nano-fabrication processes earlier developed for thermoplastic forming of polymers. The origin of the processability in length scales spanning from 10-2 to 10-7 m is the gradual softening from a solid-like material (glass) below Tg to a liquid-like material above Tg. It is one aim of the Network to develop deposition, casting, molding, and annealing techniques to obtain a whole range of vitrified metals from nanometers to centimeters thick and their composites, including porous metals.
VitriMetTech comprises five Research Projects which are designed to achieve the following objectives either employing transition-metal-based or light-metal based alloys:
1) Development of vitrified ferromagnetic alloy compositions and composites with low magneto-mechanical coupling for use in inductors and toroid-shaped or flat transformers and other energy-efficient electromagnetic devices.
2) Development of magnetostrictive vitrified ferromagnetic alloy compositions able to convert magnetic energy into mechanical energy and vice versa for magneto-mechanical coupling applications as sensors, switches and energy harvesting devices. The Network proposes ground breaking technology to replace the active element in certain sensors with high magnetostriction metallic glasses.
3) Development of low stiffness, biocompatible Ti, Zr, and Mg-based bulk vitrified metals for implants free of toxic elements to minimize stress-shielding effects and allow good load transfer to the bone which help stimulate new bone formation.
4) Optimize the corrodibility or corrosion resistance of metallic glasses for either dissolution/activation (e. g. in body fluids) or long-term use in devices. Metallic glasses are suited as precursors in a variety of catalytic applications: surface activated electrocatalysts, powders for water cleaning and de-alloyed nanoporous metals. The catalytic and spectroscopic application of metallic glasses and their nanostructured derivatives need to be explored. De-alloyed materials are tested for implantable electrostrictive actuators.
5) Increase the resilience of BMG’s and suppress shear banding and heterogeneous plastic deformation. BMG’s are known to be brittle and to fail via the action of shear bands where the temperature can rise up to melting. It is aimed at i) mapping out the experimental conditions for shear band melting which is critical for mechanical response of vitrified metals, ii) determining the size of the plastic zone and consequently the critical thickness to attain ductile fracture behavior (high toughness) in submicron microscopic application for acoustic actuators, sensors, switches and springs, iii) developing thicker bulk metallic glasses BMG based in Mg and Ti having potential application as light and strong parts in various fields from implants to aerospace, iv) developing Fe- and Co-based BMGs with mechanical strengths between 3 and 5 GPa that constitute the hardest metallic materials ever discovered.