In April we did some TEM work on Ni-Mn-Sn based and aluminium doped samples. The aluminium content was 1 and 2 atomic %. The first sample with 1 at. % of Al nicely showed typical for this materials Heusler structure composed of four interpenetrating bcc sub lattices. What is more in the grain boundary areas we spotted martensite precipitates in a form of characteristic martensitic plates. This is not a surprise since according to recent studies by Chen et al. Al increases martensite start transition temperature by decreasing the unit cell volume. It was then justified to expect even more martensitic plates in the sample stuffed with 2 at. % of aluminium. TEM later confirmed this expectation. The sample revealed a two phase structure, with one of the phases being 4O martensite. We made several BF images and STEM too in order to determine the average grain size.
This month I also gave a talk on my research work and up to date progress. No need to say that I delivered in a bravado style!