Hi all,
I hadn't seen this post but I am glad that people are getting up to speed wrt my nightmare.
The CaO:Al2O3 ratio of inclusions in steel is of primary importance to assessing the performance of the inclusion modification process of Al2O3 inclusions in steel.
But... The Ca:Al ratio is a horrible coupled situation as a function of particle size. I hope to present some of this at the AMAS.
The best work in this area is by Chris Pistorius and Nareem Verma in the Microscopy and Microanalysis Journal sometime in 2011. This showed the effect of inclusion shape, size and kV and also the effect of the spectrometer location. The work also shows the effect of the embedded nature of the inclusion centroid i.e. what he calls caps, hemispheres and truncated spheres.
Have a look at his work, it will make most analysts attempting to analyse small inclusions in a matrix with strong correction effects a bit wobbly at the knees.
WRT the Ca:Al in the inclusions, it's a horribly complicated analytical system and unfortunately, there are also thermodynamic reasons why the chemistry of the inclusions may well behave in this manner too. A classic microanalysis connundrum at the boundaries of resolution. PhD anyone?
Les