Rick Karnesky

I am currently a postdoc at Sandia National Laboratories.

I am originally from Richland, WA. It was there that I first developed an interest in materials science--through blacksmithing. I earned my Bachelor of Science degree from the California Institute of Technology in 2002 in Engineering and Applied Science. I studied materials science there. I worked at the Laser Interferometer Gravitational Wave Observatory at Hanford for one summer. I then did research with Assistant Professor Ersan Üstündag's group, including work for the Spectrometer for Materials Research at Temperature and Stress at Los Alamos National Lab.

At Northwestern University, I studied Al-Sc alloys with additional rare earth elements, which are heat resistant. The rare earth additions are expected to change the aging behavior and properties of the precipitates. In addition to performing creep experiments and simulations, I employed Transmission Electron Microscopy and 3-Dimensional Atom Probe Microscopy to study the microstructure of the material.

I also concluded a study of aluminum-scandium (Al-Sc) and aluminum-scandium-zirconium (Al-Sc-Zr) alloys that are reinforced with alumina (Al₂O₃) particles. The several nanometer Al₃ScZr precipitates and the sub-micron Al₂O₃ both strengthen the alloy. These high temperature aluminum alloys can be used effectively up to at least 350 C.

The precipitates are formed after aging the alloy which was conventionally cast with master alloys. Particle reinforcements are added by Dispersion Strengthened Casting (DSC) by Chesapeake Composites. I then studied the mechanical properties of the material--most notably its creep resistance. DSC-Al-Sc and DSC-Al-Sc-Zr exhibit very high threshold stresses. If the loading does not exceed these threshold stresses, the creep rate isn't experimentally measurable. I also employed dislocation climb and detachment models in order to explain this behavior.

Research

Dispersion Strengthened Cast aluminum-scandium alloys.

Education

B.S., Engineering and Applied Science, California Institute of Technology

Contact

phone:	925.294.2106
fax:	925.294.3410
e-mail:	sandia.gov for work gmail.com for personal
address:	MS-9403 Sandia National Laboratories 7011 East Ave. Livermore, CA 94550

Selected Honors

First prize at the 2007 John E. Hilliard Symposium
Walter P. Murphy Graduate Fellow, Northwestern University
Director of Residence Life and Master of Student Houses Award, Caltech

Affiliations

Publications and Presentations

R. A. Karnesky, et al., "Criteria for Consistent Steady-State Coarsening," Scripta Materialia, in preparation.
R. A. Karnesky, et al., "Best-Fit Ellipsoids of Atom-Probe Tomographic Data to Study Coalescence of γ' (L1₂) Precipitates in Ni-Al-Cr," Scripta Materialia, 57 , 353-356 (2007).
R. A. Karnesky, et al., "Direct Measurement of 2-Dimensional and 3-Dimensional Interprecipitate Distance Distributions from Atom-Probe Tomographic Reconstructions," Applied Physics Letters , 91 , 013111:1-3 (2007).
R. A. Karnesky, et al., "Strengthening Mechanisms in Aluminum Containing Coherent Al₃Sc Precipitates and Incoherent Al₂O₃ Dispersoids," Acta Materialia, 55 , 1299-1308 (2007).
R. A. Karnesky, et al., "Creep of Al-Sc Microalloys with Rare-Earth Element Additions," Materials Science Forum , 519-521, 1035-1040 (2006).
R. A. Karnesky, et al., "Effects of Substituting Rare-Earth Elements for Scandium in a Precipitation-Strengthened Al 0.08 at.% Sc Alloy," Scripta Materialia, 55, 437-440 (2006).
E. Ustundag, et al., "Dynamical diffraction peak splitting in time-of-flight neutron diffraction," Applied Physics Letters, 89, 233515: 1-3 (2006).
R. A. Karnesky, et al., "Mechanical Properties of a Heat-Treatable Al-Sc Alloy Reinforced with Al₂O₃ Disperoids," in Affordable Metal-Matrix Composites for High-Performance Applications II, edited by A. B. Pandey, et al. (TMS, Warrendale, PA, 2003), pp. 215-224.
E. Ustundag, et al., "Effect of Beam Divergence on Strain Data from Neutron Diffraction," presented at Denver X-ray Conference, (Denver, CO, 2002).

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