Friday, 11 October, 2013, 07:47 Posted by Zbigniew Starowicz
In the end of the last month I was on the internship within the Erasmus programe. The internship was conducted in TUBITAK MAM in Gebze in Turkey.Main topic of this period was organic solar cells : the cell formation technology and addition of matal nanoparticles to the hole transporting layer from PEDOT:PSS. For first we tried 70nm particles solution from ICSC PAS but the results were worse for sample with particles than for reference cell. U to 20% of efficiency enhancement was obtained for gold nanoparticles. But the efficiency increase was caused by the Voc increase rather than photocurrent, which was decreased. Thus we explain this results as a series resistance drop due t the nanoparticles presence
Conference report (SIM 2013) J.Poplewska
Tuesday, 8 October, 2013, 11:11 Posted by Jagoda Poplewska
I participated in 'The 41th School of Materials Science and Engineering' in 24-27.09.2013 in Krynica (Poland). The conference was organized by AGH University of Science and Technology. The scope of the conference covered fields of materials science such as: iron-based alloys, non-ferrous alloys, surface engineering, welding engineering, oxidation and corrosion, ceramics, composites and polymers, plastic deformation, functional materials. In this conference around 130 participant were attended. My participation in the 41th school was related to the presentation of research results of AA1050 aluminium alloy and delivered in a 10 minutes presentation titled: ‘ Microstructure and texture evolution during annealing of AA1050 aluminium alloy pre-deformed in ECAP ’. One of the goal of this conference was integration PhD students involved in the field of ‘Materials Science’. In the conference papers was published my article (in polish): - J. Poplewska, H. Paul, A. Tarasek, K. Berent: Zmiany mikrostruktury i tekstury podczas wyzarzania stopu AA1050 wstepnie odksztalconego w procesie ECAP. Materialy Konferencyjne XLI Szkoly Inzynierii Materialowej, Krakow-Krynica 2013, s. 444÷449. Below the abstract of this article: MICROSTRUCTURE AND TEXTURE EVOLUTION DURING ANNEALING OF AA1050 ALUMINIUM ALLOY PRE-DEFORMED IN ECAP Abstract The main aim of the experiment was to analyze the microstructure and texture evolution during recrystallization of commercial AA1050 aluminum alloy. The samples were processed by ECAP in six passes along route A and then annealed for 1 hour at temperatures ranging from 100°C to 350°C. Studies carried out using scanning electron microscopy equipped with local orientation system and X-ray diffractometer. The obtained results showed that at lower annealing temperatures, the material retains ultra-fine grain structure formed by ECAP. At higher temperatures rapid grain growth appears and transformation of flattened grains into nearly equiaxed was observed. The results showed that obtaining the fine-grained and homogeneous structure of equiaxed grains, is problematic. Keywords: AA1050 Aluminium alloy; ECAP; Recrystallization; Grain growth; EBSD
Tuesday, 8 October, 2013, 09:39 Posted by Piotr Drzymala
With regard to process the data from the various improvements made ​​EBSD . First cut off background for calculating pole figures , which was not as significant to the quality of these figures , but significantly accelerated the calculation. Cut-off backgrounds , however, it is always advisable because it can contribute to the formation of certain artifacts in the calculation of intergranular relationships . An example might be if only the angle of disorientation , but more on that in later reports . Secondly entered the correct scaling pole figures - now scaled is not every pole figure separately, but all have a common scale , which determines the maximum of the most intense pole figure . This allows for an unambiguous assessment of the texture on the basis of a statement such as the three pole figures - in the case study of alloy AZ31 is the dominant component (0001 ) < 11-20 > . Thirdly, efforts were made to improve the calculation of pole figures at the expense of a reduction in accuracy. For this purpose, a histogram of all orientations dividing the space orientation of the cube and assigning each cube orientation in the middle of such a cube and a strength associated with the number of counts orientation that went to the ankles. This whole operation takes place quite rapidly , and the restoration of the pole figure as sorted data . Qualitatively goes under , but not enough for symmetrical structures - eg ortorombowych - is a problem with playing these figures. As we know the structure of orthorhombic symmetry operators have four , but they do not work well in comparison with eg Labotexem . Diffraction measurement introduces an additional symmetry associated with the indiscernibility planes hkl and - hkl . It was found that the multiplication of the symmetry operators results in the correct symmetry of the pole figures . Perhaps this is the solution to this problem .
PhD report (September 2013) J.Poplewska
Monday, 7 October, 2013, 13:51 Posted by Jagoda Poplewska
In september I carried out in LaboTex software the analysis of global textures measured by X-ray diffractometer. I was also working on preparing 2 presentations and I gave a speech: - first for the Seminar in PAS presenting the progress of PhD research (20.09.2013) titled: 'Role of low-angle boundaries in microstructural and textural transformations during annealing of severely deformed aluminum alloys', - second connected with participation in the conference 'The 41th School of Materials Science and Engineering' (24-27.09.2013) titled: 'Microstructure and texture evolution during annealing of AA1050 aluminium alloy pre-deformed in ECAP'.
Monday, 7 October, 2013, 10:39 Posted by Jakub Kawalko
In beginning of september I was busy preparing for internal evaluation of progress in PhD research, so i had a good chance to review my recent investigations. Additionally I have prepared and submitted an abstract for upcoming Joint PhD seminar. Abstract was prepared for poster presentation that would concern general observation of microstructure features observed in KoBo deformed hexagonal metals - zinc and titanium. Microstructure investigation have been performed by high resolution SEM FEG Quanta microscope with integrated EBSD system. In cases of both types of materials microstructure after deformation is substantially refined and strongly heterogeneous, with grain sizes ranging from tens of microns to single microns size. Strong axial texture is characteristic for all kinds of examined samples with 0001 basal planes aligned parallel to the extrusion direction. Grains are typically elongated in extrusion direction, however grain shape parameter varies between zinc and titanium. Internal subgrain structure is found for both deformed material types, consisting of crystal lattice bending, resulting in slight misorientation variation along grain axis, as well as formation of dislocation walls and low angle grain boundaries.
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