Papers by Author: Beata Dubiel

Abstract: Quantitative analysis of γ' and γ" phase nanoparticles in Inconel 718 was performed using FIB-SEM tomography. Three-dimensional visualisation showed that γ' particles are spherical, while γ" precipitates are disc-shaped. The dependence of the particle size of both phases on the heat treatment applied was detected. It was proven that the FIB-SEM tomography is a very precise method for metrology and morphology investigation of nanoparticles precipitated in Inconel 718 superalloy.

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: The aim of the present work was to determine the influence of air plasma spraying (APS) parameters on the microstructure of thermal barrier coatings (TBC) consisting on NiCoCrAlY bond coat and yttria - stabilized zirconia (YSZ) top coat. The scope of the investigation involved macroscopic observation and microstructural analysis by means of light microscopy (LM) and scanning electron microscopy (SEM). For the varied parameters of deposition process quantitative analysis of coatings thickness, porosity, oxide inclusions, metallic inclusions, globular inclusions and cracks were performed. The results of quantitative analysis allowed to establish which APS conditions influence the particular microstructural parameters of TBC coatings.

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: TEM studies of the ex-service single crystal blade were performed to analyse the microstructural changes which control the degradation of the CMSX-4 superalloy during its exposure in a gas turbine. Microstructural analyses were focused mainly on evolution of the γ-γ’ morphology and examination of dislocation configurations in particular parts of the blade. Between the bottom and tip locations of the blade a pronounced differences in γ-γ’ morphology were observed. TEM analysis of the dislocation substructure showed that at the bottom of the blade the dislocation slip is mainly confined to the horizontal γ channels. Increasing of the temperature and decreasing of stress along the blade height resulted in the γ-γ’ rafting, formation of dislocation networks and intensification of the dislocation climb in vertical γ channels.

Abstract: In the present work a quantitative analysis of γ' and γ" phase nanoparticles in Inconel 718 was performed using two methods of electron tomography, namely EFTEM and FIB tomography. 3D visualisation showed that γ' particles are spherical, while γ" precipitates are disc-shaped. The values of mean size of γ' and γ" phase particles, determined by both electron tomography methods applied, are in good agreement.