In april I took part in the 15th Seminar „COMPOSITES 2011 - Theory and practice” (Spala, 27-29 of April 2011). I gave a presentation there entitled “Microstructure and properties of 7475 aluminium alloy matrix nano-composites with 10-20% Al2O3 or AlN additions”.

I am also a co-author of an article which was published under the same title in Composites
(11: 2 (2011) pp. 142-146). Below you can find a short abstract of this article.

MICROSTRUCTURE AND PROPERTIES OF 7475 ALUMINIUM ALLOY MATRIX NANO-COMPOSITES WITH 10-20% Al2O3 OR AlN ADDITIONS
Marta Gajewska, Jan Dutkiewicz, , Lidia Litynska-Dobrzynska, Jerzy Morgiel
Abstract
The microstructure and properties of two types of 7475 aluminium alloy matrix composites - with additions of 10-20 wt. % of nano-Al2O3 or AlN were investigated. The composites were produced through powder-metallurgy processing. Pre-alloyed 7475 aluminium powders were mixed with ceramic particles and milled in a high energy planetary Fritsch ball mill for up to 40 hours. Next, they were compacted at 380°C and 600 MPa. The microstructure of the obtained composites was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The performed investigations proved that both types of composites show a good dispersion of ceramic phases. The composite matrix was characterized by a fine grain size, i.e. less than 100 nm and contained a high density of intermetallic, Zn, Cu or Fe rich phases. The EDX chemical analysis indicated the local presence of an MgO phase at the metal/Al2O3 and metal/AlN interfaces. The microhardness of the compacts were in the range of 315-355 HV and 250-280 HV range for composites with micro-AlN or nano-Al2O3, respectively. It indicates that the size of the nano-crystalline matrix and intermetalic precipitates play a more important role than that of the reinforcing ceramic particles.

At the beginning of this month I went to an RMS meeting in Duesseldorf. It was about electron backscatter diffraction (EBSD). I have learned a few interesting things and found some new ideas during that conference. After coming back I faced problems the FEG in the microscope ending its life. The time when the FEG was off was spend on reading literature about new things I learned in Duesseldorf. Luckily the source was replaced for a new one in the middle of April and I could go back to work. I have been trying to do some measurements of a sample made of Al6013 after intense deformation. Additionally, I was practicing polishing samples surface with FIB. It enables to get smoother surface with better diffraction quality comparing to mechanical polishing. However, it consumes a lot of time. Unfortunately, I was not able to accomplish measurements because it turned out that the stage movement precision is poor. Probably some mechanical parts are worn out and have to be replaced. It is still possible to do regular things, but for the 3D EBSD the sample must always go back to exactly the same place when it is moving between milling and data collection positions during measurement.

In April 2011 I attended in the following seminars:
1.04.2011
- M.Sc. Eng. Maciej Szczerba in public defense of the dissertation: “Structure and magnetic properties of single crystal alloys”;
- Associate Professor Jerzy Morgiel: “Development, characterization and properties of composites produced with nano-materials”;
- Associate Professor Piotr Ozga: “Utility of Thermodynamics in electrochemistry”
8.04.2011
- M.Sc. Eng. Michal Trebala: “'The migration of potassium in potassium ferrite and its application to the surface optimization of catalytic materials”';
-- M.Sc. Eng. Anna Maria Janus in public defense of the dissertation:”'Morphology of natural hydroxyapatite intended for biological applications”.
- Professor Henryk Paul: “‘Instability of plastic flow and their role in texture transformations in fcc metals”’
15.04.2011
- Prof. Janice M Barton, Prof. Ole Thybo Thomsen: “Nonlinear Thermomechanical Behaviour of Polimer Foam Cored Sandwich Structures”';
- Professor Pawel Zieba: “‘Mass and charge transport in polycrystalline materials”’
29.04.2011
-M.Sc. Marcela Trybula: “'Applying the theory of free volume to model the thermodynamic density and size”';
- Associate Professor Lidia Litynska-Dobrzynska: “Development of aluminium alloys”

In April 2011 I also continued the study of hydrogen release on different surfaces from citrate solutions. Surface-limited kinetics of hydrogen release are derived for arbitrary surface coverage (Fe, Zn,Sn). The experiments were carried out and controlled by means of PARSTAT 2273 potentiostat. Voltammetric curves were determined under various hydrodynamic conditions by the rotating disc electrode technique. The results of all carried out tests, and plans for further research were discussed in detail with the tutor Prof. Associate. dr hab. Piotr Ozga.

1. Attending in seminars:
- M.Sc. Eng. Michal Trebala: 'The migration of potassium in potassium ferrite and its application to the surface optimization of catalytic materials';
- Prof. Janice M Barton, Prof. Ole Thybo Thomsen: ‘Nonlinear Thermomechanical Behaviour of Polimer Foam Cored Sandwich Structures';
- M.Sc. Marcela Trybula: 'Applying the theory of free volume to model the thermodynamic density and size';
- M.Sc. Eng. Maciej Szczerba in public defense of the dissertation: 'Structure and magnetic properties of single crystal alloys';
- M.Sc. Eng. Anna Maria Janus in public defense of the dissertation:'Morphology of natural hydroxyapatite intended for biological applications'.
- Associate Professor Jerzy Morgiel: 'Development, characterization and properties of composites produced with nano-materials';
- Associate Professor Piotr Ozga: 'Correlation between ceramics microstructure and functional properties';
- Professor Henryk Paul: ‘Instability of plastic flow and their role in texture transformations in fcc metals’ (second meeting);
- Professor Pawel Zieba: ‘Mass and charge transport in polycrystalline materials’ (second meeting);
- Associate Professor Lidia Litynska-Dobrzynska: ‘Development of aluminium alloys’ (second meeting).

2. Surface preparation of three samples (grinding on abrasive papers and polishing) and a study of the microstructure in the scanning electron microscope (FEI XL30 E-SEM) Aluminum alloy with 2.7% magnesium and 0.5% zirconium to confirm the well-selected saturation temperature and aging . Three samples were saturated at a temperature of 610 ° C and cooled in water and in turn each of them has been tempered by annealing at 300 ° C separately for 1, 3 and 24 hours. Observation of each of the microstructures revealed no precipitation, so it may be the treatment process parameters were not properly matched or separation is so small that the resolving power of microscope used was insufficient. Measurements will be repeated on a different microscope.

3. Stady of the book which has been bought to the project:
Haldar, Arunansu; Suwas, Satyam, Bhattacharjee, Debashish (eds.), Microstructure and texture in steel and other materials, Springer Publishing, London 2009. It contains materials from the International Conference under the same title (held 5-7.02.2008r. in Jamshedpur, India) and it consists of six chapters, headed respectively: Introduction, Control of Texture and Microstructure in Steels, Modeling, Specialized Characterization Techniques Texture and Microstructure Development During Special Processes and Materials, Contributory Papers, which in the first place are the most interesting chapters I, II, V and VI.

My research:

Composite powders - 7475 aluminium alloy powder with 10 wt.% and 20 wt.% addition of aluminum nitride powder subjected to high energy ball milling - were compacted in a VEB 40 hydraulic uniaxial press in a mould placed in a vacuum and heated using a high frequency generator. Discs about 5mm thick, 20 mm in diameter were obtained after hot pressing in a vacuum of 10-2 bar, at a pressure of 600 MPa and temperature of 380oC.
The microstructure of the hot compacted composites was characterized using an FEI E-SEM XL30 scanning electron microscope and a Tecnai G2 F20 (200kV) transmission electron microscope equipped with an integrated EDAX system. Thin foils for TEM investigations were prepared by mechanical polishing, dimpling with a Gatan Dimple Grinder (Model 656) and finally ion Ar milling with a Leica EM RES101 system.
Microhardness Vickers measurements were performed using a CSM-Instruments tester.

Seminars/meetings:

Third meeting of “Local Composite Platform”:
- presentation on ”Mechanical properties of metal-ceramics cast composites” by Pawel Kurtyka
IMMS seminars:
- “Investigations on the catalytic Au/TiO2 modelsystem” by Piotr Bobrowski
- “Atomistic simulations of the process of phase separation in the Fe-Cr system” by Rafal Abram,
- “Influence of technological factors on the wettability of soldering” by Artur Kudyba.