September 14th GBE Meeting

On Wednesday evening I picked up Yuan Jin from the airport, the PhD student working on the GBE/Formatting project at CEMEF Nice, France. The following day I finally had the opportunity to meet my future adviser Nathalie Bozzolo as well as future group mate Andrea. I suppose the word "future" is no longer appropriate seeing as we've all now met in person and had the opportunity to discuss research ideas.

Today consisted of meeting between Andrea, Yuan, Nathalie, Greg, Tony, and I, going over a variety of topics. We started on Andrea's presentation was on inhomogenous grain growth in Ni-based superalloys. The word "inhomogenous" is an interesting choice because the more research that is being done, the less "abnormal" abnormal grain growth seems to appear. In his particular work, Andrea was studying how deformation levels as well as the sub-solvus annealing temperature influences the inhomogenous grain growth. The other point of interest in these inhomogenous grains are the large number of twins present (which relate back to Yuan and I's work). This is also a very particularly interesting work because these inhomogenous grains occur with the presence of the Delta-phase, making us question the role the solute drag. Or the major question in addition to why do they occur, is also why do they stabilize and stop?

Yuan gave a presentation afterwards on some data analysis on samples prepared by Thomas, a Master's student working at CEMEF. In this study, the annealing twin density based on the average grain size distribution was studied. Grain size was manipulated by both the initial deformation level, as well as the recrystallization temperature. These samples were dynamically recrystallized and followed the trend behaviors as predicted by Pande. The purpose was to possibly look into how grain boundary velocity may be playing a role to the twinning mechanism. Tony mentioned Carl Necker's inadvertent anneal, which raises the question again of whether it is grain boundary velocity or temperature that is the contributing factor.

The rest of the afternoon consisted over going both of our paper submissions for the 5th International Recrystallization and Grain Growth Conference. Needless to say, my initial draft was picked apart by my advisers, however, that is always quite the learning experience.

Somethings that were mentioned and need to be done:

• How can we related the moving boundary plane to the the (111) twinning plane?
• How can we partition to look at the boundary of deformed and recrystallized grains from GOS?
• To follow up, what sort of behaviors do we expect to observe at the interface
• Use of DSC furnace of rapid thermal anneals of sample to cut down on time
• Probability of Sigma3 boundary occurring based on every 50 grains in a volume of space
• Observe the number fraction and length fraction during both recrystallization and grain growth and how these two regimes differ from each other
• Determine a way to measure the connectivity of twin length fractions (as discussed yesterday with Professor Rohrer)

On another note: First conference paper submitted...

Can't wait until May...