Nanostructures

Motivation

Materials with a grain sizes less than a micrometer exhibit outstanding mechanical properties, because their material behavior is predominantly determined by their internal interfaces. The fields of application of such materials are applications with particular requirements concerning ductility and strength. On materials, we distinguish between nanocrystalline materials with an average grain size of up to 100nm and ultra fine grained materials with an average grain size in the range of 100nm to 1 µm.

Research focus

A smart and approved method to produce massive nanocrystalline materials is to use a strong plastic shear strain, which is usually the "Equal Channel Angular Extrusion" (ECAP). This method has been developed in UFA/ Russian Federation, being published by Prof. Valiev. The deformation structure of highly deformed materials and their thermal stability should be investigated.

Methods
  • CEM (EBSD)
  • TEM

Simulation of Composites

Motivation

The single crystal aluminium oxide fiber (sapphire) reinforced NiAl and NiAl alloys are suggested to be used as a core material of blades in gas turbine machines, which should resist a stress of 150MPa for 500,000 hours at 1000 °C. A BN intermediate layer was introduced into the composites in order to modify the interface structure and property. Al2O3 /NiAl (FG75) and Al2O3 /BN/NiAl(FG75) are therefore extensively investigated composite systems.

Research focus

Interface structure and properties are of prime importance for the properties of the composites. Hence, the studies focus on the interface structure and interface chemistry, as well as mechanical properties at room temperature and elevated temperature.

Methods

Microstructure investigations by optical microscopes, electron microscopes (SEM, TEM) and microanalysis (XEDS, EELS, SAD and EBSD) have been utilized for investigations. Whereas mechanical properties of the composites have been determined by push-out test, bending test and tensile test.


Composites Properties

Motivation

The single crystal aluminium oxide fiber (sapphire) reinforced NiAl and NiAl alloys are suggested to be used as a core material of blades in gas turbine machines, which should resist a stress of 150MPa for 500,000 hours at 1000°C. A BN intermediate layer was introduced into the composites in order to modify the interface structure and property. Al2O3/NiAl (FG75) and Al2O3/BN/NiAl(FG75) are therefore extensively investigated composite systems.

Research focus

Interface structure and properties are of prime importance for the properties of the composites. Hence, the studies focus on the interface structure and interface chemistry, as well as mechanical properties at room temperature and elevated temperature.

Methods

Microstructure investigations by optical microscopes,electron microscopes (SEM, TEM) and microanalysis (XEDS, EELS, SAD and EBSD) have been utilized for investigations. Whereas mechanical properties of the composites have been determined by push-out test, bending test and tensile test.