October 12th 3D HEDM Data

High Energy X-Ray Diffraction Microscopy (I believe I've mentioned it previously before) is an amazing technique which allows non-destructive 3D characterization of a microstructure. Chris Hefferan recently defended his thesis on studying the annealing of pure nickel. This is very similar to my project, although at the same time a more general understanding of whether this technique can be used to observe grain growth changes as well as any change in the grain boundary character. Of course, the most readily apparent observation is the saturation of Sigma3 boundaries in the microstructure. This was further investigated to determine if it was just the increase volume of Sigma3 boundaries in the microstructure, or if more boundaries were becoming closer in alignment to the Sigma3 nature. It turned out that the first had very little contribution, while the second played a much more major role.

I recently obtained a copy of the data of the sample in its fourth annealing state. The goal is to compare the twin morphologies found in this 3D data set to both what Yuan and I were trying to achieve, and any other data set we can find out there, and determine a scheme for classifying twins in 3D.

The .vtk file of the data is 2.5 GBs.

...

ParaView has crashed two or three times dealing with the size of this data, but the few times I have managed to get it to fully work, this thing is an absolute monstrosity. The number of grains in the sample are impressive as well as their well-defined shape prior to any smoothing/meshing. There are well over 10,000 grains in the system, which each time I attempt to threshold the sample, I watch in fear of the rainbow cursor spinning indefinitely. However, here are some preliminary attempts, in which we can clearly see we conserve the corner twin on the left and the complete twin regardless of how we approach the slice:

What's immediately interesting already is the lack of well defined, straight coherent twin boundaries. Instead, depending on both how and where we slice it, we can have different degrees of steps/facets in the 2D image. Back to more investigation!

October 8th MS&T 2012

Is being held here in Pittsburgh!

It actually started yesterday, although I was pre-occupied with sending both my father and Yuan to the airport, and the rain discouraged me from coming out again later in the evening.

Attending in-town conferences always present a difficulty in balancing between classes (which I decided to ditch), research work (some last minute SEM work), and sessions. And with all that, there's the other difficulty of picking which sessions to attend due to overlaps.

That being said, I did attend some very good and novel talks on grain boundary quantification, specifically looking at the topology of grain boundary networks as well as how to further/properly classify triple junctions from stereology. It'll be hard to find someone doing the exact same work as you (after all that is research), but there will always be similarities. However, in most cases, I find that these talks simply either reinforce what I already know, or challenge me to think a little bit harder about what my data is showing. Intrinsically, this might be a little bit of a research competition kick to think what can I show or prove better.

The talks that I come away with the most are normally those that aren't related to my research directly though. They're indirectly related in that their objective is looking for another method of characterization (typically through heavy mathematics). Although the reasoning behind this is most likely due to the fact that annealing twins have more or less been very well documented now (despite the lack of explanation still for the last hundred years). Therefore it isn't that we need more experimental work necessarily, but more ways to consider how we approach the problem and what we're looking for. I consider how these ideas can be applied to my own research then, and very generally what information it may provide that is different from what we haven't seen already.

Unfortunately I will not be doing the same courtesy as I just mentioned above, but I will still be presenting a poster tomorrow.

October 7th Reflections

I dropped off Yuan at the airport today. In another month I'll be joining him there at CEMEF to perform a series of in-situ experiments. I assume that I'll be as busy there just as he was here, and probably towards the end of the exchange just as homesick. During the last few days, Yuan and I did less experimental work, but significantly more discussion between our data, our grain encounter program, and our ideas for twin formation mechanisms. We talked about each proposed mechanism, and I mentioned that it seemed impossible during our timespan to find the answer.

He quickly interjected, "That is not our responsibility. We cannot expect ourselves to change the world. Our responsibility first and foremost as PhD students is obtain our degree through doing good research."

At this point I contemplated what good research was. Isn't good research something that answers a fundamental question? Which in our case would be determining the origin of annealing twins.

Yuan told me something that Nathalie told him:

Research is the equivalent of a forest. We are completely lost, there are no paved paths that lead us, and instead we have to look for an exit ourselves. We don't know how large the forest is, we don't know what direction is right, and we don't who (or if anyone) has came through here before. All we can do is search for our way out.

That search is the one we find in research.

There is no right or wrong answer in our journey. As long as continue to trodden into uncharted territory, then we will always be finding something new.



Continue moving forward and continue exploring.

Ciao!