Lightweight Materials

Research Field Lightweight Materials

Our research focuses on development, fabrication and characterization of advanced lightweight materials and components.

Mitarbeiterfoto Peter Randelzhofer

Peter Randelzhofer, M.Sc.

Mitarbeiterfoto Jonathan Wedler

Jonathan Wedler, M.Sc.

Mitarbeiterfoto David Himmler

David Himmler, M.Sc.

Mitarbeiterfoto Yan Zeng

Yan Zeng, M.Sc.

Mitarbeiterfoto Oleksandr Trudonoshyn

Oleksandr Trudonoshyn, M.Sc.

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Technical Reports

The aim involved in designing metal matrix composite materials is to combine the desirable properties of metals and ceramics. The addition of high strength, high modulus refractory particles to a ductile metal matrix produces MMCs whose mechanical properties are excellent, such as high strength to weight ratio, high stiffness and good wear resistance. Due to these excellent attributes, MMCs are widely used in aerospace, automobiles, etc.
Among the variety of manufacturing processes available for particle reinforced aluminum materials, stir casting is generally accepted as a particularly promising approach as a result of its simplicity, flexibility, applicability to large quantity production and low costs of production. Though, in preparing particle reinforced aluminum materials by stir casting, we have to consider the following difficulties:
(1) How to achieve a uniform distribution of the reinforcement material.
(2) Promoting the wettability between the two main substances;
(3) Control chemical reactions between the reinforcement material and the matrix alloy.
A new high shear technology can be applied in producing particle reinforced aluminum materials. The aluminum melt is strongly sheared in the semi-liquid or liquid state. The high shear forces produced by a special designed impeller lead to very homogeneous dispersions of additives like particles. In addition, shearing has influence on the homogeneity of the melt and leads to finer grain structures. These effects are expected to be beneficial for the fabrication of metal matrix composites. Therefore, the particular focus of the project is to use shear device to introduce particles into an aluminum melt before die casting and the main aim is to evaluate the potential of the new high shear technology for conditioning of aluminum melts for pressure die casting.

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With Al-Mg-Si-Mn casting alloys with compositions inside of the pseudobinary section of the subsequent ternary phase diagram, the effect of Zn, Ti, Sc and Ag additions on the precepetation of nanoparticels in as-cast and heat-treated conditions as well as mechanical properties under different conditions (as-cast, solution treated, quenched andaged) will be studied. Despite of the established foundry practce of several Al-Mg-Si-Mn and Al-Zn-Mg casting alloys subjected to high pressure die casting only little research was done either on structure formation or strengthening mechanisms of these alloys and mechanical properties that can be achieved after additional alloying.

In frame of this project as cast conditions of AlMg5Si2Mn alloyed by Zn, Ti, Sc and Ag will be investigated paying attention to precipitates formed in solid solution matrix prior to heat treatment and changes of mechanical properties from as-cast state to age hardened.

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Complex 3-D carbon fibre preforms are to be infiltrated with aluminium in a high pressure die casting process. If our approach is successful, it will represent a major breakthrough compared to gas pressure infiltration, the state-of-the-art technology to manufacture fibre reinforced metal parts. Compared to the above mentioned technology, pressure die casting offers several advantages. The short cycle times characteristic for this process are not only of a substantial economic advantage, but also constrict the kinetically controlled deleterious reactions between the fibre-preforms and the aluminium matrix. Based on results of preliminary die casting experiments and numerical simulations of the infiltration process, an advanced mould design was realized in the past project phase further improving fibre preform preheating. In combination with advanced alloy compositions and fibre coatings developed by the project partners the main aims of the proposed continuation are to realize metal matrix composites (MMC) with improved transversal strength and ductility. A detailed understanding of the interface reactions is necessary to relate processing parameters, alloy and coating composition to the mechanical properties of the obtained MMC. In order to rationalise results, advanced microstructural investigations like SEM-FIB, high resolution TEM and numerical calculations of the infiltration process with Flow-3D and ABAQUS are envisaged.

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