Research Projects

We are working on understanding the underlying mechanism of hydrogen embrittlement susceptibility in a Fe 28Mn 0.3C (Wt.%) alloy on the micro and nano scale by  exploring differentt hydrogen charging routes, for instance cathodic charging, gas charging and plasma charging. The defect behavior (dislocation density and arrangement, stacking faults, twins, ε-martensite, residual stresses) is investigated using deformation experiments coupled with electron channeling contrast imaging (ECCI) technique in both charged and uncharged conditions.Local residual stresses are measured with cross-correlation EBSD.In order to investigate the role of grain boundaries and stacking faults as hydrogen trapping sites, we also perform site-specific atom probe tomography (APT) studiesafter charging the samples with hydrogen/deuterium. more

Backscatter Kikuchi diffraction patterns (or EBSD patterns) contain much more information about the diffracting crystal than just the crystal orientation. In particular, they carry information about the crystal metrik and about the density of defects at the illuminated area. The crystal metrik (i.e. the lattice parameters) can be determined from an exact analysis of the band position. Information on the defect density is obtained from an analysis of the band profile. more

Cadmium telluride (CdTe) is efficiently used for solar energy conversion in the form of thin film solar cells. Its particularly well-fitting optoelectronic properties (almost ideal bandgap, high absorption coefficient and high thermal stability) are still driving the interests of both scientific communities and industrial companies in the highly competitive world of photovoltaic materials. An extended knowledge of the layer microstructure formation is expected to lead to process-optimization to continue to push back the current world record of 21 % efficiency. more

Grain boundary chemistry and mechanics more

One of the key players that controls hardening and fracture toughness of AHS steels is the crystallographic character distribution and morphology of grain and phase boundaries. This project aims at understanding and optimizing crystallographic, morphological, and chemical properties of such boundaries in AHS steels in order to improve the mechanical behavior of the material. more

ECCI and XR-EBSD is applied to study the grown-in dislocations at interdendritic boundaries of a nickel based single crystal superalloy and their evolution during creep. more

Solar thermal power plants transform the sun light collected by large mirrors into thermal energy. The high amount of energy concentrated in the mirror focus is transferred, in an absorber block, to liquid salt circulating through pipes of steel or superalloys. Liquid salt corrodes, in particular, the grain boundaries of these material. Understanding and controlling grain boundary corrosion in molten salt is, therefore, crucial. more

Quench and Partioning (Q&P) steels are 3rd generation advanced high strengths (AHS) steels. They consist of a martensite-austenite microstructure created during a quenching process. However, due to the subsequent partitioning treatment the martensite is relatively soft and the austenite relatively stable against phase transformation which makes the alloy strong (tensile strength up to 1000 MPa) and ductile (uniform tensile elongation up to 20 %) at the same time. We aim at improving the microstructure by obtaining finer austenite dispersion. more