Yaron Amouyal

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Yaron Amouyal
Research: Freckle formation in Ni-based superalloys
Education: Ph.D., Technion - Israel Institute of Technology
M.Sc., Technion, Israel
Publications: Publications by Amouyal in our database


Dr. Yaron Amouyal
Materials Science and Engineering
2220 North Campus Drive
Evanston, IL 60208
Phone: 847.467.5698
Fax: 847.467.2269

I graduated from the Technion – Israel Institute of Technology (Ph.D.) and joined Prof. David Seidman group in August 2007 as a post-doctoral fellow. My current research activity is investigating the formation of defects during the solidification of Ni-based superalloys applied for turbine blades in aeronautical jet engines. Common defects occurring during the directional solidification of these single-crystalline blades are long chains of grains that are highly disoriented with respect to the matrix, and are referred to as “freckle chains”. Freckles may cause degradation in the alloy mechanical properties at high-temperatures, and therefore should be avoided. Besides this technological challenge, the persisting effort being made in the technology of jet engines is elevating their working temperature in order to improve their thermodynamic efficiency. The latter implies a demand for improving these alloys high-temperature creep and oxidation resistance. Both problems strongly depend on the alloy composition and morphology in the nanometer length scale. For this purpose, we apply the latest version of the three-dimensional Atom Probe Tomography (APT), namely the Local-Electrode Atom-Probe (LEAP). Our strategy is to produce an array of tips (microposts) from the region of a freckle (several millimeters in size), and to characterized each one of them individually by the LEAP. While a single tip has the lateral dimensions of several micrometers, the typical analysis volume obtained by the LEAP is tens of nm cube (~10M atoms). Additional characterization techniques, such as TEM, are being applied in order to span length scales. In this manner we hope to characterize the morphologies and chemistries of individual defect-rich zones at all pertinent length scales down to the sub-nanometer scale, which may help us understanding the role that each alloying element plays in the nucleation of freckles. This information will be used as input data for ab-initio Molecular Dynamics (AIMD) simulations of the thermodynamics of these alloys, and will enable us to formulate predictive models for the conditions where freckling can be avoided.

Combination of Atom Probe Tomography (APT) and Density Functional Theory (DFT) to investigate atomistic-level phenomena in nickel-based superalloys