Functional Magnesium Materials
Simulation of filling a cast spiral. Photo: HZG
The area of process technology comprises all activities concerned with the casting of magnesium-based materials. This applies not only to production of wrought and cast magnesium alloys but also to alloy development and further processing in the molten and partially fluid states.
The main areas of research are:
- constitution of magnesium alloys,
- investigation of the castability of magnesium alloys, grain refinement, rheology, and hot tearing susceptibility,
- in situ solidification experiments with synchrotron radiation,
- development of high temperature-resistant magnesium materials, recycling alloys, biodegradable magnesium alloys, and nanoparticle reinforced magnesium composites,
- replacement of rare earths as alloying elements.
Intermetallic network in the interdendritic space in Mg10Gd1Nd. Photo: HZG
All technological activities concerning the production and processing of magnesium-based materials by means of casting are performed in the Processing Department, headed by Dr. Norbert Hort, in Magnesium Innovation Centre MagIC. This applies to alloy development, the manufacturing of magnesium alloys, and further processing in the molten and semi-solid state.
- Development of high temperature-resistant magnesium materials, recycling alloys and biodegradable magnesium alloys: A barium containing magnesium alloy has recently been invented and patented. It shows excellent creep resistance, which is comparable with that of aluminium alloys. There is still no recycling route existing for magnesium alloys. Therefore the development of such alloys with well-rounded properties is a focus of our department. Sr, Ca and Zn are added to Mg-Al-Mn alloys in order to prove their useability as recycling alloys. Use of magnesium alloys as biodegradable implants offers a new field of application for magnesium. Mechanical properties of magnesium alloys are close to that of bone. Furthermore magnesium alloys degrade in the body. The desolved products are not harmful to the body. These materials can act as implants for a certain time and desolve afterwards. A second surgery for removal is thus not necessary.
- Replacement of rare earth elements: Rare earth elements are used to make magnesium alloys more stable at high temperatures and less flammable. They are also critical from ecological and economical pioints of view. We replace them by other alloying elements or ceramic additions.
- In-situ studies of solidification and phase formation with synchrotron radiation: Solidification behaviour of magnesium alloys is investigated by synchrotron radiation for the first time. It provides information about the solidification sequence and the evolution of the morphology of the phases.
- Nano-sized reinforcement of magnesium alloys: Reinforcement of magnesium alloys with nanoscale ceramic particles and related improvement of properties is a further focus of our group. Applying an ultrasound process creating cavitation to the melt helps to incorporate the particles or carbon nanotubes. Creep resistance and high temperature strength are improved significantly.
- Investigation of the castability of magnesium alloys; grain refinement, rheology and hot tearing susceptibility: Castability is an important issue for all magnesium alloys. Different techniques are applied for testing and determination of castability. The goal of the work is to characterize the influence of chemical composition and cast parameters on the fluidity and solidification behaviour of different magnesium alloys. Grain refinement is important for production of advanced magnesium wrought alloys. Currently we focus on SiC as grain refiner. However, the refining mechanism is still not fully understood.