Marco Witte

Salzgitter Mannesmann Forschung · Materials Characterization

X-ray fluorescence (XRF) is frequently used to measure layer thickness in the micrometer range. But also X-ray diffraction (XRD) can be used in a comparable way and offers the benefit to differentiate coating layers by their crystal structure. Thus, the thickness of different oxide layers of the same element can be determined, e.g., FeO, Fe 3 O 4 ,...

The description of the solidification process in casting processes with varying product thickness is characterized based on solidification structures, segregations as well as the primary and secondary microstructure. In near-net-shape casting processes, it is particularly challenging to achieve microstructure homogeneity in the as-cast condition, s...

In der Stahlindustrie werden neue Werkstoffe unter anderem hinsichtlich ihrer Zähigkeit und Duktilität optimiert. Deren technologische Kennwerte werden insbesondere durch die Größe, Form und Verteilung kohlenstoffreicher Gefügebestandteile wie Martensit, Restaustenit und Karbide beeinflusst. Ihre effiziente und gleichzeitig präzise Beschreibung ist...

In-situ XRD experiments allow to investigate microstructural changes at elevated temperatures and to collect large amounts of data in a short time. In order to carry out such measurements a XRD with area detector was equipped with a commercial heating stage. The aim is to determine the range of possible in situ XRD applications and to optimize the...

EBSD sample preparation recipe for steel, problems with electropolishing, inhomogeneity & measurement position, metastable Austenite and grain statistics.

Es wird gezeigt, wie sequentielle EBSD-Messungen hoher Qualität mit einem EDAX-System an mehreren Proben durchgeführt werden können. Hierzu werden ein Visual Basic Skript und Remote Software von EDAX und Zeiss kombiniert. Die damit erzeugte große Anzahl an Messdaten wird mittels MTEX/Matlab automatisch hinsichtlich Korngrößen, Textur, Phasenanteile...

The effect of severe plastic straining by HPT processing on the mechanical properties and the microstructure evolution of a commercial AA 6082 alloy was studied. The HPT processing was carried out by torsion of 0.5 rotation per minute under 2 GPa load, for up to 5 turns. The material was solutionized before HPT. Mechanical homogeneity is achieved a...

In the scope of the optimization of multi phase steels, e.g. for the automotive industry, control of the microstructure is essential to tailor the mechanical properties. In this study, two cold rolled steels varying in carbon content were annealed and cooled under different laboratory conditions. The microstructure is investigated using optical and...

Abstracts The aim of the joint industrial and academic project “SupraMetall” is to enable the large scale production of superconducting tapes. This is a report of the recent achievements in the production of cube textured metal substrates and the coating techniques of the buffer and superconductive layers. The final coated conductor tapes of 2 m le...

For the application of Ni-5at.%W as substrate for high-temperature superconductors the development of a very intense Cube texture is essential. Therefore, the texture development in Ni-5at.%W was studied in detail by experiments and computer simulations. Cold rolling of the material resulted in a pronounced Beta-fiber texture which transformed by r...

The growth of abnormally large grains in textured Ni-5at.%W substrates for high-temperature superconductors deteriorates the sharp texture of these materials and thus has to be avoided. Therefore the growth of abnormal grains is investigated and how it is influenced by the grain orientation and the annealing atmosphere. Texture measurements and gra...

A new measurement strategy is introduced to determine very pronounced crystallographic textures of polycrystalline materials most accurately and efficiently. It features optimized adaptively refined successive X-ray pole figure measurements. To optimize both the total experimental time as well as the angular resolution, and thus the accuracy of pol...

The mechanism of charge generation in transition metal oxide (TMO)-based charge-generation layers (CGL) used in stacked organic light-emitting diodes (OLEDs) is reported upon. An interconnecting unit between two vertically stacked OLEDs, consisting of an abrupt heterointerface between a Cs2CO3-doped 4,7-diphenyl-1,10-phenanthroline layer and a WO3...