June was month of samples preparation for the calorimetric analysis to determine thermal stability of coatings in the temperature range from-50oC to +50oC. Similar heat treated specimens were analyzed on scanning electron microscope to assess if any changes in surface morphology took place. This month I participated in AMT 2013 conference and gave a talk about chemical control of polyelectrolyte film properties for an effective cardiovascular implants endothelialization, during session dedicated to young scientists. I also took part in the confocal microscopy workshop. During the course I listened to lectures about methods dedicated to cellular adhesion and migration in vivo observations. Practical part of workshop was divided into three sessions. I get more familiar with cell movement analysis by the resonance scanning confocal system, calcium ions flow investigations by spinning disc microscopy and methods of image processing by deconvolution and 3D reconstruction.

Last month I took part in two international conferences:

- XX Physical Metallurgy and Materials Science Conference: Advanced Materials and Technologies – AMT 2013 in Kudowa-Zdrój, where I was given an opportunity to give a speech during Young scientists session, which was entitled: “Characterization of reaction products of liquid Al and Mg3N2”

- 17th International Conference on Composite Structures in Porto, were I also gave a talk, but this time on “Effects of heat treatment on microstructure and microhardness of ball milled/hot pressed Al 7475/AlN nano-composites”

My activities in June:

During this month I have prepared publication entitled: Structural investigation of Mg-3Ca, Mg-3Zn-1Ca and Mg-3Zn-3Ca wt.% as cast alloys.

Here you have an abstract:

Magnesium alloys from Mg-Zn-Ca system are interesting, because of possible application as bioresorbable cardiovascular stents or temporary orthopaedic implants. Avoidance of removal surgery is an undeniable advantage of using biodegradable materials.
Alloys of nominal composition Mg-3Ca, Mg-3Zn-1Ca and Mg-3Zn-3Ca (in wt.%) have been prepared by resistance melting and casting into graphite mould under protective argon atmosphere. All investigated alloys have revealed (Mg) dendritic microstructures with intermetallic phases distributed in interdendritic spacing. Except a(Mg), hexagonal ternary phase Ca2Mg6Zn3 has been detected for the Mg-3Zn-1Ca alloy and Mg-3Zn-3Ca (Ca2Mg6Zn3 phase belongs to the space group P63/mmc, with lattice parameters depending on the chemical composition). It was calculated that the unit cell parameters for the ternary phase change - a: from 9.912 to 9.945 Å, c: from 10.351 to 10.378 Å, if compare Mg-3Zn-1Ca to Mg-3Zn-3Ca. The Mg-3Ca alloy contain only Mg2Ca (hexagonal crystal structure; space group P63/mmc, with lattice parameters a = 6.239 Å and c =10.146 Å). The same binary phase has been identified in Mg-3Zn-3Ca alloy, but with slightly changed parameters:
a = 6.2152 Å and c = 10.0699 Å. The hardness of all alloys have been measured. The highest value: 68 HV has been observed for Mg-3Zn-3Ca alloy whereas hardness of alloy containing only calcium was significantly lower: 49 HV. Both existing in materials intermetallic phases segregate on the grain boundaries and harden alloys.

Based on the results of the research of local orientations measured by EBSD/SEM for AA1050 and AA3004 aluminum alloys (made in the system y-x: for cross-section ND-TD or TD-ND) I made studies of transformation of these data into rolling system TD-RD and I created a tool to verify correctness of these transformations. Based on the analysis of texture data for the calculated percentage shares texture components defined as: 'Copper','S', 'Goss','Brass',I could draw the following conclusions:
- You can get data on percentage shares of individual texture components in the rolling system (for plane TD-RD) by performing measurements of local orientation (EBSD maps) in a plane perpendicular to the RD direction (RD is parallel to ED in ECAP die) and transforming it accordingly;
- The analysis of change of texture components in function of 1-hour annealing temperature (from 100°C to 400°C) for AA1050 and AA3004 aluminium alloys showed no correlation (too small region taken to the measurement);
- To obtain reliable data, the measurement should be made over a larger area - should cover a wider range of microstructure (our area was 10x10µm2);
- Verification of the results should always be made based on a different method of measurement, in our case, we will survey the entire surface of the sample using X-ray diffractometer.

I decided to deal with the heat of my solutions. Cooling them were not so easy. I found that the labortory refrigerator had cooled my reagents to 17 degrees C (at room temperature over 25). The effect was pour - a little smaller pits on the surface. I'm looking for a better way of effective mixture cooling. The second thing was etching the nanoporous layer with 1 M KOH. After that, the nicely textured wafers with low reflectivity, returned to the base materials reflectivity of more than 30%, what troubled me a lot. Generally, this month was not really successful...