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Determination of UTW K/sub XSi/ factors for low atomic number microanalysis: A systematic approach

Description: A systematic measurement of experimental K/sub XSi/ factors, with particular emphasis on low Z microanalysis (6 less than or equal to 7 less than or equal to 32), at 200 kV for a KEVEX UTW Si(Li) detector fitted to a JEOL 200CX analytical microscope, using a variety of high purity standards has been carried out. Under normal operating conditions of a LaB/sub 6/ filament, it is shown that absorption in the specimen is very critical, particularly for heavy element matrices, and sample thicknesses need to be measured for accurate microanalysis of low Z elements (C,N,O). Using these measured K/sub XSi/ factors, quantitative UTW-EDX microanalysis has been routinely extended to carbon. 21 refs.
Date: July 1, 1987
Creator: Krishnan, K.M. & Echer, C.J.
Partner: UNT Libraries Government Documents Department

Measurements of ionization cross-section for electron energy-loss microanalysis under well defined scattering conditions

Description: Partial cross-sections required for electron energy-loss microanalysis have been measured for a series of high purity single crystal standards. For each sample four different scattering geometries were used. The experimental data were compared with theoretical calculations using both standard hydrogenic model and parametrized Hartree-Slater cross-sections. Best agreement between theory and experiment were observed for experiments performed in diffraction mode (image coupling) with the probe convergence angle (0. 84 mrad) much smaller than the spectrometer collection angle (6.84 mrad). In addition, specimen thicknesses from the region of microanalysis were measured by convergent beam electron diffraction. Absolute cross-section based on these measurements are also currently being determined. 10 refs., 2 figs.
Date: April 1, 1991
Creator: Krishnan, K.M. & Echer, C.J.
Partner: UNT Libraries Government Documents Department

DT fusion neutron radiation strengthening of copper and niobium

Description: The initial results of a comparative study of the radiation strengthening and damage structures produced in Cu and Nb by D-T fusion and fission reactor neutrons are described. The radiation strengthening produced by a given fluence of fusion neutrons above about 10$sup 17$ n/cm$sup 2$ is equal to that produced by a fluence of fission reactor neutrons (E greater than 0.1 MeV) ten times as great. This difference is about twice as large as would be expected if the strengthening scaled with damage energy or dpa. Initial transmission electron microscopy observations of the damage structures in fusion and fission reactor neutron irradiated copper indicate that the same type of primary structural defects, vacancy and interstitial point defect clusters and small dislocation loops with a/3 (111) and a/2 (110) Burgers vectors, are produced in both cases. The difference in the radiation strengthening produced by fusion and fission reactor neutrons in Cu appears to result from a substantially greater rate of accumulation of damage, in the form of point defect clusters, during irradiation with fusion neutrons than during irradiation with fission reactor neutrons plus a significant difference in the size and spatial distributions of the damage clusters. (auth)
Date: September 29, 1975
Creator: Mitchell, J.B.; Van Konynenburg, R.A.; Echer, C.J. & Parkin, D.M.
Partner: UNT Libraries Government Documents Department

DT fusion neutron radiation strengthening of copper and niobium

Description: The initial results of a comparative study of the radiation strengthening and damage structures produced in Cu and Nb by D-T fusion and fission reactor neutrons are described. The radiation strengthening produced by a given fluence of fusion neutrons above about 10$sup 17$n/cm$sup 2$ is equal to that produced by a fluence of fission reactor neutrons (E greater than 0.1 MeV) ten times as great. This difference is about twice as large as would be expected if the strengthening scaled with damage energy or dpa. Initial transmission electron microscopy observations of the damage structures in fusion and fission reactor neutron irradiated copper indicate that the same type of primary structural defects, vacancy and interstitial point defect clusters and small dislocation loops with a/3 (111) and a/2 (110) Burgers vectors, are produced in both cases. The difference in the radiation strengthening produced by fusion and fission reactor neutrons in Cu appears to result from a substantially greater rate of accumulation of damage, in the form of point defect clusters, during irradiation with fusion neutrons than during irradiation with fission reactor neutrons plus a significant difference in the size and spatial distributions of the damage clusters. (auth)
Date: October 30, 1975
Creator: Mitchell, J.B.; Van Konynenburg, R.A.; Echer, C.J. & Parkin, D.M.
Partner: UNT Libraries Government Documents Department

Energy-beam processing studies on Ta/U and Ir/Ta systems. [Laser-and electron-beam melting]

Description: Films of Ta metal on uranium and of Ir metal on tantalum have been irradiated and melted by pulses from Q-switched Ruby and frequency-doubled Nd:YAG lasers to investigate the nature of the resulting mixtures in light of the very different binary-phase diagrams of the two systems. In addition, a two-phase Ir-Ta alloy has been surface-processed with CW CO/sub 2/-laser radiation and with an electron beam in order to study microstructure refinement and test the advantage of using alloys as opposed to film-on-substrate combinations for the development of claddings.
Date: November 11, 1983
Creator: Kaufmann, E.N.; Peercy, P.S.; Jacobson, D.C.; Draper, C.W.; Huegel, F.J.; Echer, C.J. et al.
Partner: UNT Libraries Government Documents Department