Bulk Nanocrystalline Metals and Alloys

The nanostructuring of bulk metallic materials is obtained by top-down structuring using extremly large strains achieved by plastic deformation under enhanced hydrostatic pressure ("Severe Plastic Deformation, SPD").

Therfore "High Pressure Torsion, HPT" is  primarily used as hydrostatic pressure can be varied and strain can be applied continuously and unlimited.

Subsequently the measurement & understanding of the increased mechanical properties (strength, ductility, fatigue strength, fracture thoughness) as a function of grain size and annealing treatment is of main interest.

X-ray Profile Analysis (XPA)

The microstructural features like grain/subgrain-size and -distribution, the dislocation density and also planar lattice defects of nanostructured materials produced by severe plastic deformation but also by other processing routes (electro- and vapor deposition, crystallization from amorphous state,..) are analysed by X-ray Bragg profile analysis.

The microstructure is characterisd "ex-situ" after processing and/or thermal treatment using an especially designed home laboratory diffractometer but a special focus lies in the devlopment of in-situ experiments using high brilliant Synchrotron radiation.

High Entropy Alloys (HEA)

These are materials that consist at least of 4-5 alloying-partners/elements in equal amount. Due to Gibbs free energy of formation (ΔG) and the high configurational (mixing) entropy the material may crystallize in one single phase, mostly with high symmetry (fcc or bcc).

The HEAs exhibit high strength, good ductility, increased low temperature deformation properties, good corrosion resistance and also good fatigue properties are predicted. However, many basic principals are not investigated yet, especially with regard to the many different alloys that can be constructed.

Functional properties of nanostructured materials

The improvement of following functional properties of materials by applying by severe plastic deformation is investigated:

Hydrogenated nanomaterials: processing by SPD; hydrogen storage, ab- and desorption, stabilization of lattice defects by hydrogen

Thermoelectric nanomaterials: chemical synthesis, processing by ball-milling and SPD, structural analysis and characterization, thermoelectric properties

Magnetic nanomaterials: processing by ball-milling and SPD, structural characterization, soft and hard magnetic properties

Plasticity of Polymers

The microstructural features and mechanisms of plastic deformation in polymers with semi/nanocrystalline and amorphous structure are investigated with respect to dislocation dominated plasticity in the crystalline phase.