A Metallic Lightweight
Scientists are extending the range of uses of magnesium by rolling the light metal into sheets. Foto: HZG/Christian Schmid
It’s the lightweight amongst metallic construction materials: magnesium is much less dense than steel or even aluminium – compared with the latter, it’s around one third lighter. Indeed, magnesium is actually in use today, for instance in laptop casings and in vehicle construction. Until now, magnesium has not been able to be processed into sheets on a large scale. However, in order to practically exploit the lightweight-construction potential of magnesium, the production of large-scale structures is required. Such sheets of magnesium alloys can be shaped into readymade components, such as car doors. The alloys and processes necessary for this are being developed at the Helmholtz-Zentrum Geesthacht.
The search is on for alloys that can be shaped easily into components, are resistant to corrosion and are of suitable strength. In addition, processes are being developed that can be used to manufacture and process the sheets efficiently and thus economically. Scientists are pursuing various strategies to improve the ductility of materials.
New alloys and procedures
Specialists are lacing their alloys with materials such as gadolinium, yttrium or neodymium. These rare-earth elements refine the microstructure and improve the material. However, these elements should really be replaced if at all possible for ecological and economic reasons. This is why the researchers are looking for alternatives and are trying out calcium, for example. These appear not only to improve the ductility but also appear to increase corrosion
At the same time, researchers are developing processes that clearly simplify the production of sheets and simultaneously improve quality. In a so-called twinroll casting process, the magnesium-alloy casting and rolling process are directly merged. This produces a thin magnesium strip, which is shaped into sheet at a final gauge using a few conventional rolling stages. This saves many of the steps in the classic production route. The material should additionally be easy to recycle. The recycling of scrap metals is worthwhile both ecologically and economically, and protects resources.
Lightweight engineering with magnesium
Magnesium sheet metals can be produced with the institute’s own casting-rolling unit (“RollMag”) and can subsequently undergo scientific study. We are thus moving closer to the economic application of magnesium sheet metals.
A protective layer for metal
In contact with aggressive environments magnesium tends to corrode quite quickly. It is especially critical when this light metal is joined with other conductive materials to form components. Galvanic corrosion can easily occur in the contact areas. The materials researchers are focusing on new types of protective coatings, such as ceramic layers and polymers, which can offer an active corrosion protection to magnesium and multi-material components.
New materials for light-weight construction
How to further slim down cars and airplanes? Scientists at the MagIC explore the potential of magnesium as light weight material.
Perfect ligthweight material
Until now, magnesium has been mainly used in the form of gearbox casings, engine parts, covers, seat elements or fittings. Future areas of use lie in the construction of entire vehicles and aircraft as well as in the area of electronics, as components in the computer, camera and mobile-phone industries. The range of components has been greatly expanded with the new rolled alloys.
Scientists in the “Magnesium Innovation Centre” of the HZG have extensive opportunities for their research: in addition to laboratories to manufacture the smallest sample quantities, they also operate a continuous casting and rolling plant on a semi-industrial scale. In addition, they have various methods of analysis available, such as microscopy and test stands for load tests.