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Will, W. Hoffman, Mark P. 2011-06-02T16:56:51Z 2011-06-02T16:56:51Z 10000-01-01 1987 A brief review of the basic physics of electron energy loss spectroscopy and extended x-ray absorption fine structure spectoscopy is presented in the context of their application to the study of the microstructure of transition metal carbides and diborides. The local atomic structure of amorphous titanium diboride thin films, prepared by electron beam vaporization of the crystalline compound onto liquid nitrogen-cooled substrates, is examined using extended x-ray absorption fine structure (EXAFS) and extended electron energy loss fine structure (EXELFS). The extended fine structure spectra of the amorphous films are compared with corresponding spectra for crystalline titanium diboride. A relaxation of the interatomic spacing and a reduction of coordination numbers for nearest neighbor atoms is observed for the amorphous state. Local prismatic coordination with random 90° rotations about prismatic planes is presented as a likely atomic structure for the amorphous state. The high-temperature hardness of crystalline tantalum carbide is linked to the presence of extended stacking faults. Suzuki hardening limited by bulk carbon diffusion is presented as the mechanism which distinguishes tantalum carbide from iv other carbides with the same structure. Softening is predicted to occur at temperatures near those observed experimentally. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-06-02T16:56:51Z No. of bitstreams: 1 1987_Hoffman.pdf: 772148 bytes, checksum: 8bbef190bd6bc460636b0f4bb277ee07 (MD5) Made available in DSpace on 2011-06-02T16:56:51Z (GMT). No. of bitstreams: 1 1987_Hoffman.pdf: 772148 bytes, checksum: 8bbef190bd6bc460636b0f4bb277ee07 (MD5) Previous issue date: 1987 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-06-02T16:56:51Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:14:19-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Thesis U of I Only 1856879 http://hdl.handle.net/2142/25225 en 1987 Mark P. Hoffman microstructure electron energy loss local atomic structure refractory compounds amorphous titanium diboride The influence of microstructure on the mechanical properties of some refractory compounds Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.