Papers by Author: Adam Kruk

Abstract: Due to aggressive gases produced during combustion process of biomass, some elements of the power boiler should be covered with a material that possesses very high corrosion resistance (e.g. Inconel 625). This paper presents results of microstructural studies of Inconel 625 padding weld on waterwall elements (made of 13CrMo4-5 steel) for steam boiler designed for biomass combustion. The microstructural studies were carried out using Scanning- as well as Transmission Electron Microscopy methods. The padded weld layer exhibited dendritic structure. In the weld layer γ phase with an increased dislocation density and stacking faults was observed. In the base material (13CrMo4-5 steel) titanium nitrides, complex carbides and Laves phase enriched in niobium were observed.

Abstract: STEM-EDX and FIB-SEM tomography studies have been carried out to visualize three-dimensional morphology of the γ’ precipitates in different zones of ex-service turbine blade made of CMSX-4 single crystal superalloy. The results allowed the three dimensional analysis of the changes in microstructure of blade as resulting of operating conditions. Tomographic reconstructions provided quantitative data about γ and γ’ phase shape, size and volume fraction. It was shown that FIB-SEM tomography technique is suitable for 3D reconstruction of the objects of 100 nm in size or even smaller and thus enables the accurate quantitative microstructural analysis of this superalloy.

Abstract: TEM, HAADF-STEM tomography and FIB/SEM tomography studies have been carried out to visualize three-dimensional morphology of the oxide dispersoids in ferritic ODS alloy INCOLOY MA956. Electron tomography results provided quantitative data about particle shape, size and distribution of the particles, complementary to those obtained by means of quantitative TEM metallography. It was shown that FIB/SEM, a meso-scale tomography technique, is suitable for 3D reconstruction of the objects of 100 nm in size or even smaller.

Abstract: The electron tomography and transmission electron microscopy studies of the carbides in the 0.5Cr-0.5Mo-0.25V (13HMF) low-alloy steel after service during 160 000 h at 540 °C were carried out. Identification of the carbides was performed by means of electron diffraction analysis. Meso-scale tomography technique, mainly FIB/SEM tomography, was used for detailed characterization of spatial distribution and metrology of the carbides in 13HMF steel. The results achieved confirm the ability of FIB tomography to get 3D reconstruction of internal microstructure of steel as well as to obtain information about the shape and spatial distribution of carbides.