Main studies carried out during July:

- preparation of ribbons with zirconium addition for observation with Scanning Electron Microscopy by embedding in resin, polishing, sputtering with thin carbon layer. As a result of microscopy investigation inhomogeneous structure of obtained ribbons was observed (as in previous obtained ribbons)
- preparation of new alloys with addition of the following elements: V, Ti, Mo, Cr
- observation of prepared ingots microstructure, determination of chemical composition of observed phases with SEM
- obtaining ribbons from prepared ingots by melt-spinning technique
- TEM investigations of Al-Mn-Fe ribbon in as-cast state and after annealing
-preparation of the article for 39th School in Material Science in Krynica, Poland (26-30 September): “Microstructure, mechanical properties and thermal stability of Al-Mn-Fe melt-spun ribbons” and an abstract: „Characterization of Al-Mn-Fe melt-spun ribbon” for publication in “Archives of Metallurgy and Materials”.

My research in July:

Investigation of samples of 7475 alloy powder sintered in argon or nitrogen atmosphere at different temperatures (600 deg.C, 620 deg.C, 630 deg.C, 640 deg.C, 650 deg.C were used for argon atmosphere and 540 deg.C, 570 deg.C, 590 deg.C for nitrogen atmosphere).
Before sintering, green compacts of milled AA7475 powder (with 1% of glycerin addition) were prepared by uniaxial cold pressing at 300 and 400 MPa.
Metallographic specimens from cross-sections of sintered samples were prepared by mechanical grinding and polishing using 3 µm, 1 µm and 1/4 µm diamond suspensions.
Microstructure observations of prepared samples were carried out using metallographic microscope.

TEM observation of AlN nano-powder used for new 7475/AlN composites preparation by powder metallurgy technique.

Preparation for the exams in following subjects:
“Introduction to materials science”
“Thermodynamics - engineering approach”.

In july I mainly focused on studying the Electrochemical Impedance Spectroscopy (EIS). EIS is a method of characterizing electrochemical systems. This technique measures the impedance of a system over a range of frequencies, and therefore the frequency response of the system, including the energy storage and dissipation properties, is revealed. Often, data obtained by EIS is expressed graphically in a Bode plot or a Nyquist plot. EIS is universal and commonly used method used to studying the rate and the mechanisms of electrode processes and to determine the characteristic of interface electrode/electrolyte. I could use this method to study the processes of electrodeposition of metals, electrochemical characteristic of alloy layers and to study of the corrosion processes.

I participate in „Theory and Practice of Elektrochemical Impedance Spectroscopy” summer school in Bath University (19th -22nd July 2011).

On the training I listened the following lectures:

-Network analysis. An introduction to Linear Ciruit Analysis and Circuit Elements”; Dr Frank Marken (University of Bath);
-“Frequency response analysis”; Professor Laurie Peter (University of Bath);
-“Introduction to Electrochemical Instrumentation”; Dr John Harper (Solartron Analytical);
-“Electrical Properties of Materials”; Dr Jason Riley (Imperial College London);
-“Impedance of Electrochemical Systems”; Dr Toby Jenkins (University of Bath);
-“Spectroelectrochemical Impedance”; Dr David Fermin (University of Bristol);
-“Solartron Systems: Extreme Impedance”; Dr John Harper (Solartron Analytical);
-“The uses of equivalent circuits”; Professor Stephen Fletcher (Loughborough University);

and I also attended in the following lab sessions:

• "Seeing those sine waves”
• "Getting to know the equipment”
• „Fitting the software"
• "The impedance properties of a simple redox reaction: the ferri/ferrocyanide couple"
• "Characterisation of a lead-acid battery by EIS"
• Studying corrosion by EIS" (part I)
• Studying corrosion by EIS" (part II) "Practical Impedance Spectroscopy: measurement of polymer film porosity and corrosion"
• "Studying the dye sensitized solar cell (DSC) by Impedance spectroscopy"
• "The impedance Characteristic of Polyaniline
• Studying of Porous Electrodes and Supercapacitors by EIS".

In June I was continuing 3D-EBSD measurements on the severely deformed aluminum alloy from previous month. Additionally, an attempt to investigate a PLZT ceramic sample was made. These ceramics can be interesting because of the ferromagnetic effect occurring in them. This effect is connected with rotation of domains within grains upon magnetization of the sample. The EBSD techniques can be useful in observation of these changes of orientation within grains. Unfortunately, no indexable diffractions were observed on these ceramics. It is, probably, because of the damage of the samples surface, introduced by FIB polishing during preparations to the 3D measurements. Luckily, it turned out that, after cautious polishing, it is possible to obtain good quality diffractions and the investigations will be continued next month.
I took part in the conference entitled: “The XIVth International Conference on Electron Microscopy” which was held in Wisła in Poland. I presented a poster there. Its title was: “Three-dimensional OIM-FIB technique: selected application examples”. The abstract of the poster is givein below.

Abstract
K. Berenta, M. Bieda, A. Bigos, P. Bobrowski, M. Faryna
Three-dimensional orientation microscopy is an important tool for properties analysis of fine grain materials. The technique of 3D reconstruction of serial sections has been used to determine grain shapes, particle distributions and microstructure evolution. Fully automated 3D orientation microscopy system combines FIB and EBSD in the SEM allowing the collection of serial section of OIM data. Two examples have been selected for presentation of the 3-D FIB-OIM system capabilities: a) electrodeposited Ni coatings containing a few percent of Mo additive, b) aluminum 6013 alloy after severe plastic deformation. Nickel coatings were prepared by electrodeposition on stainless steel substrate from citrate solution. These coatings are a promising alternative to the chromium ones which, due to their toxicity, have to be eliminated from manufacturing processes. Aluminum 6013 alloy was subject to complex deformation by the KOBO method which combines extrusion with simultaneous twist of the sample. The resulting material possesses a gradient structure of the grain size distribution with fine crystallites in the outer part and elongated ones near the centre of the rod. The experimental parameters and measuring conditions were established for both materials. Along with EBSD measurements the changes of chemical composition using EDX spectrometry in 3D has been recorded. A special attention has been paid to Ga+ ion distribution as intense ion beam radiation may destroy aluminium microstructure after severe deformation. Additionally, a few attempts have been made to collect the EBSD data from serial sections of the structure of non-conductive PLZT ceramics- a piezoelectric, transparent material with wide range of potential applications.

Main studies carried out during June:

- Investigation of crystallographic orientation relationship between matrix and quasicrystalline phase in Al-Mn-Fe melt-spun ribbon, as a result relation i5<001>&#945; was observed in the 5-fold diffraction pattern, further investigation of eutectic composition by STEM analysis showed that it has slightly different composition comparing to the quasicrystals with spherical and dendritic shape.

- Preparation of the articles (4 pages), poster and presentation for the following conference: The XIVth International Conference on Electron Microscopy in Wisla.

- Participation in the conference mentioned above between 26-30th of June. During conference oral presentation was given at the Young scientist session (as 1st award for Best Ph.D student’s abstract) - „TEM study of quasicrystals in Al-Mn-Fe melt-spun ribbon”. Participation in poster session where two posters were presented. The first one with the title corresponding to the topic of oral presentation, the second one: „Microstructure and properties of hot compacted Al-12 wt% Zn-3wt% Mg-1.5% Cu melt spun ribbons”. Attendance in lectures during following sessions: electron diffraction, highlights in TEM, holography, SEM, defects, materials and nanomaterials.

Participation in seminar performed by M.Sc. Eng. Lukasz Rogal about thixo-cast steels.