The article send to 'Materials Science Forum':

'Early stages of recrystallization in ECAP-deformed AA1050 alloy
investigated by SEM orientation mapping'

Jagoda Poplewska, Henryk Paul, Katarzyna Berent

Keywords: nucleation & recrystallization, AA1050 alloy, ECAP, second phase particles, orientation mapping;

Abstract
Early stages of recrystallization were observed for the technical purity aluminium
alloy (AA1050). The samples were severely deformed by equal channel angular pressing and then annealed to obtain the state of partial recrystallization. The nucleation of new grains and the changes in ‘density’ of low- and high- angle boundaries were analysed using scanning electron microscopy equipped with high resolution EBSD system. After deformation in six passes along route A the alloy contained a structure of flat grains. On annealing, the structure coarsened and got transformed into nearly equiaxed grains by both discontinuous and continuous recrystallization. A particular role in the rise of nuclei and the structure spheroidization is attributed to migration of low-angle boundaries.

In October I performed experiments in order to assess thrombogenicity and lymphocytes activation by alginate and poly-L-lysine modified capsules. This beads could be immobilized on the polyelctrolyte multilayer surface and applied as an effective carriers for various growth factors stimulating HUVECs proliferation. I also prepared samples for Impact R test. Moreover I carried out hemocompatibility analysis in the radial flow chamber on silicon rings covered by titanium carbo-nitride, titanium dioxide or diamond-like carbon coatings.

We started to characterize the ribbons containing Al substitution in place of tin by SQUID measurements. These results will allow the study of the magnetic properties of the alloys.

With respect to the studies carried out in August (AFM and profilometer) additional tests were performed using confocal microscopy. The investigations showed that the sample etched in a solution of 8HF:1HNO3:1H2O volume ratio for 60 seconds was characterized by a normal regular surface microstructure consisting of the oval holes ranging in size from a few to tens of micrometers. This means that the resulting structures are considerably higher (approximately twice) than those observed for the wafers etched in the 7:2:1 solution at a the same time. This result can be advantageous from the point of view of the wafers fragility and surface defects etching. The slopes of the resulting holes are smoother while maintaining optimal shape. Holes depth were estimated to a few microns to the maximum of 10.

Actually I have done nothing spectacular this month. I started to work with two example data sets: yttria and nickel superalloy. I spent a lot of time playing with various parameters that can be set in the software for data clean-up and boundary surface reconstruction. I developed a part of computer software for calculating the distributions, but as for now, there is something wrong with them... to be continued next time...