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Staff

David T. Hoelzer

Research Staff
Alloy Behavior and Design Group
Materials Science & Technology Division
Oak Ridge National Laboratory
P.O. Box 2008
Oak Ridge, TN 37831-6136
Phone: (865) 574-5096
Fax: (865) 241-3650
email: hoelzerd@ornl.gov

 

Research Interest:

Development of advanced high-temperature materials with emphasis on understanding the relationship between processing, microstructure and mechanical properties; the analysis of microstructures using analytical electron microscopy (AEM) focusing on understanding the crystallography of phases and the solid-state phase transformations; and the mechanical alloying processing.

Education:

  • Ph.D. in Materials Science and Engineering, University of Florida, Gainesville, December, 1996.
    Dissertation - "Phase Transformations in the Central Portion of the Nb-Ti-Al Ternary System."
  • M.S. in Materials Science and Engineering, University of Florida, Gainesville, December, 1991.
    Thesis - "The Effect of Copper and Nickel on the Neutron Irradiation Damage in Iron Alloys."
  • B.S. in Materials Science and Engineering, University of Florida, Gainesville, August, 1985.
  • Senior Research - Investigated the ductile crack initiation process for an A-543 pressure vessel steel by correlating the stretch zone width with the crack tip opening displacement of the crack.

Employment History:

Research Staff Member in the Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN. May 2000 to present. Focus of current and past research project:

  • Principle investigator of several projects that led to successful development of the advanced oxide dispersion strengthened 14YWT ferritic alloy that contains a high concentration of nano-size Ti-, Y- and O-enriched clusters, or nanostructures. The focus of current projects includes: investigating the creep and fracture toughness properties of 14YWT; understanding the deformation mechanisms of 14YWT, especially those occurring during creep at high temperatures; examining alternative processing technologies that will enable the scale-up production of 14YWT to facilitate future fabrication and joining studies; and investigating the stability of the microstructure and mechanical properties of 14YWT during energetic ion and neutron irradiations to high doses and temperatures.
  • Investigated the relationship between microstructural texture and recrystallization behavior of Nb-1Zr and showed that texture could influence the creep behavior of this alloy.
  • Investigated the solute interactions between Ti and interstitial O, C and N impurities by studying the dynamic strain aging deformation behavior of V-4Cr-4Ti and vanadium.
  • Investigated the precipitation behavior and developed a heat treatment procedure that redistributed the O, C and N interstitial atoms from inhomogeneously distributed coarse TiCON precipitates to homogeneous nano-plate shaped TiCON precipitates that improved the low temperature fracture toughness and high temperature creep strength of V-4Cr-4Ti.
  • Post-Doctoral Research Fellowship in the Metals & Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN. September 1998 to May 2000. Conducted research on various projects based on structure/property/processing relationships relevant to the Fusion Energy Program.
  • TEM Technical Specialist and Adjunct Instructor at the New York State College of Ceramics at Alfred University (NYSCC), Alfred, NY. August 1992 to August 1998.
  • Instructor of graduate level TEM course which included lecture and laboratory sessions covering microscope components and operation, electron diffraction, amplitude and phase contrast image formation, image/diffraction interpretation, and specimen preparation for materials science applications.
  • Worked with faculty, students, and industrial clients in the area of analytical TEM characterization. Responsible for generating and interpreting data from imaging, diffraction, and x-ray energy dispersive spectroscopy (XEDS) techniques appropriate to the needs of specific projects. Also, instructed and performed suitable specimen preparation methodologies.
  • Manager of the TEM facility: JEOL 2000FX Analytical/Scanning Transmission Electron Microscope, PGT XEDS analyzer, Gatan DuoMill Ion-Mill, Edwards carbon evaporator, other specimen preparation equipment, and photographic darkroom facilities.
  • Graduate Research Assistant - Department of Materials Science and Engineering, University of Florida, Gainesville, FL. September 1985 to August 1987 and May 1988 to December 1991. TEM Microscopist (part-time) - Major Analytical Instrumentation Center (MAIC), University of Florida, Gainesville, FL. August 1987 and May 1988.
Membership In Professional Associations:
  • Materials Research Society (MRS)
  • Microscopy Society of America (MSA)
  • ASM International
    • Executive Committee Member; Oak Ridge Chapter, 1999 to present.
    • Executive Committee Member; S.W. New York Chapter, 1996-1998.
  • Sigma Xi
  • Air Force Association (AFA)

Selected Publications