In May 2011 I continue the study of stability of homogeneous Zn(II)-Sn(II)-Mo(VI) citrate solutions and the study of electrochemical properties of citrate complexes presented in examinated solutions.
The electrochemical behavior of citrate complexes was investigated by cyclic voltammetry method. Cyclic voltammetry (CV) is one of the most commonly used electrochemical techniques, and is based on a linear potential waveform; that is, the potential is changed as a linear function of time. It offers a rapid location of redox potentials of the electroactive species. CV can be used to investigate the electrochemical properties of species.
All my electrochemical studies were carried out with PARSTAT 2273 potentiostat. The working electrode was copper disc, the reference electrode was saturated calomel electrode, and the counter electrode was platinum.
I conducted research in different hydrodynamic conditions, in the following solutions:
1) 0,65 M Na3HCit; pH=5;
2) 0,25 M Na3HCit; pH=5;
3) 0,65 M Na3HCit; 0,02 Na2MoO4; pH=5;
4) 0,65 M Na3HCit; 0,05 Na2MoO4; pH=5;
5) 0,65 M Na3HCit; 0,1 Na2MoO4; pH=5;
6) 0,25 M Na3HCit; 0,02 Na2MoO4; pH=5;
7) 0,25 M Na3HCit; 0,05 Na2MoO4; pH=5;
8) 0,25 M Na3HCit; 0,1 Na2MoO4; pH=5;
9) 0,65 M Na3HCit; 0,08 SnSO4; pH=5;
10) 0,65 M Na3HCit; 0,16 ZnSO4; pH=5;
11) 0,65 M Na3HCit; 0,16 ZnSO4; 0,08 SnSO4; pH=5;
12) 0,65 M Na3HCit; 0,02 Na2MoO4; 0,16 ZnSO4; pH=5;
13) 0,65 M Na3HCit; 0,05 Na2MoO4; 0,16 ZnSO4; pH=5;
14) 0,65 M Na3HCit; 0,1 Na2MoO4; 0,16 ZnSO4; pH=5;
15) 0,65 M Na3HCit; 0,15 Na2MoO4; 0,16 ZnSO4; pH=5;
16) 0,65 M Na3HCit; 0,20 Na2MoO4; 0,16 ZnSO4; pH=5;
17) 0,65 M Na3HCit; 0,24 Na2MoO4; 0,16 ZnSO4; pH=5;
18) 0,65 M Na3HCit; 0,30 Na2MoO4; 0,16 ZnSO4; pH=5;
19) 0,25 M Na3HCit; 0,02 Na2MoO4; 0,16 ZnSO4; pH=5;
20) 0,25 M Na3HCit; 0,05 Na2MoO4; 0,16 ZnSO4; pH=5;
21) 0,25 M Na3HCit; 0,1 Na2MoO4; 0,16 ZnSO4; pH=5;
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.
In May I also attended in the following seminars:
-6.05.2011 roku M.Sc. Eng. Sylwia Pawlak „Charakterystyka naprężeniowo-teksturowa obszarów o niejednorodnej strukturze w wybranych materiałach i elementach konstrukcyjnych” ;
- 27 maja 2011 M.Sc. Eng.. Tomasz Kruk „Ultracienkie wielowarstwowe filmy polimerowe jako wielofunkcyjne powłoki i membrany”.

Main studies carried out during April:

- Microhardness measurements of the Al91Mn7Fe2 ingot. Obtained values were lower comparing to microhardness of melt-spun ribbons prepared from this ingot.
- Further investigations of icosahedral phase decomposition during thermal treatment using TEM and XRD. During I phase transformation nucleation of Al6Mn at the quasicrystal–α-Al phase interface was observed.
- Chemical analyses of all observed phases were done using EDX microanalyser. Information about observed phases obtained by two techniques where compared in relation to the knowledge available from the scientific papers.
- Interpretation of the electron diffraction patterns obtained from observed phases using CaRIne 3.0 crystallographic software.

Participation in seminars:
- M.Sc. Eng. Michal Trebala: “Migration of potassium in potassium ferrite (β-K2Fe22O34) and its application to the surface optimization of catalytic materials”;
- M.Sc. Marcela Trybula: “Applying the theory of free volume for modeling the density and thermodynamic parameters”;
- Prof. Janice M Barton, Prof. Ole Thybo Thomsen: “Nonlinear Thermomechanical Behaviour of Polimer Foam Cored Sandwich Structures”;

Participation in public defense of PhD. thesis:
- M.Sc. Eng. Maciej Szczerba : “Structure and properties of single crystals of magnetic Ni-Mn-Ga alloys”;
- M.Sc. Eng. Anna Maria Janus :”Morphology of natural hydroxyapatite intended for biological applications”.

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.