Richard Karnesky

From Northwestern University Center for Atom-Probe Tomography

Richard Karnesky at the LEAP
Research:	Aluminum-Scandium Alloys
Education:	Ph.D., Materials Science and Engineering Northwestern University B.S., Engineering and Applied Science California Institute of Technology
Publications:	Publications by Karnesky in our database
Contact
Dr. Richard Karnesky MS-9404 Sandia National Laboratories 7011 East Ave. Livermore, CA 94550 Phone: 925.294.2106 Email: sandia.gov for work; gmail.com for personal Fax: 925.294.3410

[edit] Presently

I am a postdoc at Sandia National Laboratories.

[edit] Research at Northwestern

[edit] Al-Sc-RE

I studied Al-Sc alloys with additional rare earth elements, which are creep resistant at high temperatures. The rare earth additions change the aging behavior and properties of the precipitates. In addition to performing creep experiments and simulations, I have employed Transmission Electron Microscopy and Atom Probe Tomography to study the microstructure of the material.

This study is discussed in Effects of Substituting Rare-Earth Elements for Scandium in a Precipitation-Strengthened Al 0.08 at.% Sc and in Creep of Al-Sc Microalloys with Rare-Earth Element Additions

[edit] DSC-Al-Sc(-Zr)

I first studied aluminum-scandium (Al-Sc) and aluminum-scandium-zirconium (Al-Sc-Zr) alloys that are reinforced with alumina (Al₂O₃) particles. The several nanometer Al₃Sc,Zr 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. Conductivity measurements show that the Al₂O₃ does not change substantially the nucleation and growth of Al₃Sc,Zr precipitates I measured 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.

This study is detailed in Strengthening Mechanisms in Aluminum Containing Coherent Al₃Sc Precipitates and Incoherent Al₂O₃ Dispersoids.

[edit] Other Atom Probe Tomography

• Best-Fit Ellipsoids of Atom-Probe Tomographic Data to Study Coalescence of γ' (L1₂) Precipitates in Ni-Al-Cr
• Direct Measurement of 2D and 3D Interprecipitate Distance Distributions from Atom-Probe Tomographic Reconstructions

[edit] Previous Work

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. We recently published Dynamical Diffraction Peak Splitting in Time-of-Flight Neutron Diffraction