Modeling Inclusions/Particles Embedded in a Matrix

[Sheri Singerling]

Hi John,

I reran the MC and used a 3600 s simulation time. Here are my results for the SF contribution to concentration for S, Fe, and Ni:

S: 7.166 +/- 0.234 wt. %
Fe: -2.840 +/- 0.318 wt. %
Ni: -0.472 +/- 0.121 wt. %

The uncertainty for Ni looks a bit high so maybe I'll have to run an even longer simulation.

[Probeman]

I re-ran the C Ka in Fe99Ni1 adjacent or included in pure C for both the couple and hemisphere geometries, but using a longer integration time. That is 50K seconds versus the original 3.6K seconds per simulation as seen here:

http://probesoftware.com/smf/index.php?topic=59.msg1341#msg1341

Here are the 50K seconds simulations calculated for Penepma couple and hemisphere geometries along with the Penfluor couple calculation just for comparison:



Note that the Penepma couple calculations and the Penfluor quick and dirty model produces similar but somewhat different intensities also.

A plot shows that the couple and hemisphere geometries produce quite different k-ratios for C Ka:



The symbols without error bars have errors larger than the data values!

The data file and plot output are attached below.

Note that the hemisphere calculations were originally plotted using the diameter. They have been updated to plot using the radius.

[Probeman]

Someone asked to see the Penfluor data plotted up alongside the Penepma data for the C Ka in Fe99Ni1 adjacent to pure C and so here it is.  I added an arrow to show where the 0.5 um k-ratio intensity would plot up, but considering how steep this function is for a very, very absorbing system, the differences aren't as bad as one might think.



In fact, the k-ratio values at 2 microns and further are essentially identical (within statistics)!

As for the difference in the intensities at less than 2 um? These can probably be explained by the fact that at that distance and with a 20 keV incident beam, you'll get some primary electron scattering into the boundary phase which Penepma will handle properly, while that contribution is neglected in the SF calculation in Fanal. Why? Because Penfluor pre-calculates the PAR files for the primary excitation (and continuum fluorescence) intensities based only on composition- without geometrical considerations in its Monte-Carlo modeling. Fanal then calculates the secondary fluorescence intensities using an analytical model which assumes that all electrons come to rest in the beam incident material. More discussion on this here:

http://probesoftware.com/smf/index.php?topic=58.msg1388#msg1388

What does this mean to us?  Well we should perhaps utilize Penfluor when we need a relatively quick answer, but maybe not trust it quite so much as the interaction volume radius approaches our boundary distance.

[Sheri Singerling]

I finally managed to run the MC simulations for both a sphere geometry and a couple geometry in my Fe50Ni50 - FeS system. I used a run time of 3600 s and only did the two radii/distances from boundary since my FeNi inclusions range from 1 to 2 microns in diameter. I plotted the k ratios in addition to log K ratio since my negative values for Ni could not be plotted on the log plot. My uncertainties (represented by the vertical error bars) aren't too bad in comparison to the above example with C in Fe99Ni1!

[John Donovan]

Here are my S ka in Fe90Ni10 at 15 keV comparison between Penepma hemispheres vs. Penepma couples vs. Penfluor/Fanal couples.



The remaining values I am continuing to calculate...

I've also attached a complete set of the hemisphere geo files in case that would be useful below.
john

[Probeman]

Here is an updated plot of S Ka in Fe90Ni1 embedded in FeS2:



Just for fun I also calculated the same for Ni, which gives the following:



Not bad considering the size of the 1 sigma error bars!

Don't know why the Ni intensity drops as the boundary is approached?  A hint is here:

http://probesoftware.com/smf/index.php?topic=126.msg525#msg525

[John Donovan]

A more recent calculation of Ed's C Ka in Fe/Ni included in carbon (epoxy):



Data files attached below.

[Sheri Singerling]

Has anyone run into difficulties with simulations saying they are complete after only 21 secs? I've set my simulations to a dump time of 60 s and a simulation time of 3600 s. This has only cropped up with 2 of my 16 simulations. I don't know what's unique about these two runs (they are Fe40Ni60 and Fe45Ni55 1.25 micron spheres in FeS). Some of my other successful simulations have also been 1.25 micron spheres and also had the Fe40Ni60 and Fe45Ni55 compositions so it can't have anything to do with the .GEO or .MAT files. I've compared the .IN files of these troublesome ones to my simulations that ran without issue for 3600 s but found no difference that would explain this. I've remade the .IN files a number of times now with no improvement. Any suggestions would be wonderful!

[John Donovan]

Has anyone run into difficulties with simulations saying they are complete after only 21 secs? I've set my simulations to a dump time of 60 s and a simulation time of 3600 s. This has only cropped up with 2 of my 16 simulations. I don't know what's unique about these two runs (they are Fe40Ni60 and Fe45Ni55 1.25 micron spheres in FeS). Some of my other successful simulations have also been 1.25 micron spheres and also had the Fe40Ni60 and Fe45Ni55 compositions so it can't have anything to do with the .GEO or .MAT files. I've compared the .IN files of these troublesome ones to my simulations that ran without issue for 3600 s but found no difference that would explain this. I've remade the .IN files a number of times now with no improvement. Any suggestions would be wonderful!

Hi Sheri,
I assume this is in the Penepma window in Standard? I would first ask you to update (yes, again).
I am flying back to Eugene as I write from the Hartford M&M- sorry you didn't make it. Awesome conference!

I am running many, many, many Penepma simulations all the time and have not seen this, but maybe it's a computer specific thing.  Try another computer?
john

[Sheri Singerling]

Yes it is PENEPMA within the Standards window. I will update my penepma and see if that helps! I have an old laptop that I can try the simulation on if that doesn't fix the issue. One day I will be able to attend a conference other than LPSC or MetSoc! Wish I could've been there.

[Probeman]

Yes it is PENEPMA within the Standards window. I will update my penepma and see if that helps! I have an old laptop that I can try the simulation on if that doesn't fix the issue. One day I will be able to attend a conference other than LPSC or MetSoc! Wish I could've been there.

Just update using the CalcZAF.msi file.
john

[Les Moore]

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

[lsaper]

Did a quick search around and couldn't find anything:

For the embedded sphere geometry can PENEMPA model the matrix as the beam incident material?

e.g. For a spherical glass inclusion embedded in olivine, can we model the contribution of secondary fluorescence to Ca measurements of the enclosing olivine?

Thank you,
Lee

[Probeman]

Did a quick search around and couldn't find anything:

For the embedded sphere geometry can PENEMPA model the matrix as the beam incident material?

e.g. For a spherical glass inclusion embedded in olivine, can we model the contribution of secondary fluorescence to Ca measurements of the enclosing olivine?

Thank you,
Lee

Yes. But you need to modify the beam position:



to be non-zero.  To make it easy we recently modified the units to be microns, so be sure to update CalcZAF from the Help menu.
john

[lsaper]

Thank you for the reply and the heads up to install the latest update.

After attempting some calculations, I want to clarify whether I'm doing this properly.

I have attached a file showing a representative setup for creating the input files. The beam incident material is set to glass (the inclusion) with the matrix set to olivine (material I am interesting in calculating SF for). The geometry file is 160mic_sphere.geo and in this example I have set X = 161 (want 1 micron into the olivine from the interface) Y = 0 Z = 1. Assuming these settings are appropriate, I created several of these .in files by incrementing the X-axis beam position to obtain a profile into the matrix and ran them sequentially in batch mode. In addition I have run the same calculation on a bulk geometry (X=Y=0 Z=1) on a synthetic anorthite standard for Ca. I then used the automated "extract k-ratios" tool in the batch mode dialog to calculate the Ca K-alpha k-ratios for the modeled olivine profile, over the anorthite standard. All calculations are for 3600s.

When I run this there is a lot of scatter in the modeled K-ratios. I want to make sure that I'm doing the procedure right before running the calculations for longer. Thanks for your patience and help!

Lee