Graduate Research Assistant and Ph.D. Candidate, Missouri University of Science and Technology
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“Solute Characterization of (Zr,Ta)B2 Ceramics”
Solute segregation was examined in zirconium diboride and zirconium-tantalum diboride solid solution ceramics that were produced by reactive hot pressing. Microstructural analysis demonstrated that the ZrB2 and (Zr,Ta)B2 ceramics reached nearly full relative density and were nominally phase pure. X-ray diffraction was consistent with full incorporation of Ta into solid solution within the ZrB2 structure, and energy dispersive spectroscopy demonstrated that tantalum was well-distributed throughout the bulk of the Ta-doped specimens. The weak characteristic x-rays for B led to inaccurate results for total atom concentrations in boride ceramics by energy dispersive spectroscopy. Atom probe tomography was used to analyze the amount and spatial distribution of Ta species. No obvious Ta segregation was observed in grains or grain boundaries. However, nitrogen strongly segregated to a grain boundary. This study demonstrated that atom probe tomography is an accurate method for characterizing the amount and spatial distribution of metallic and non-metallic species in ZrB2 ceramics.
Anna Dorner, Graduate Research Assistant and Ph.D. Candidate, Missouri University of Science and Technology
Anna Dorner is currently a 4th-year Ph.D. student in ceramic engineering at Missouri University of Science and Technology, where she is a member of the ultra-high temperature ceramics research group headed by Dr. Bill Fahrenholtz and Dr. Greg Hilmas. Her graduate research interests are based in fundamental science studies of solid solution diboride materials. Her first publication on the characterization of diboride solid solutions was published in the Journal of the American Ceramic Society in December 2019, and her current research includes the effects of solute additions upon mechanical properties in ZrB2 and phase equilibria and diffusion in the ZrB2-TaB2 system. Anna was awarded “Outstanding Ceramic Graduate Student” by her department in Spring 2019. Prior to her time at Missouri S&T, she attended Purdue University where she earned a B.S. in chemistry with minors in materials science and Spanish in 2017.