[B._Beckhoff,_et_al.]_Handbook_of_Practical_X-Ray_(b-ok.org).pdf

A deformation pattern has been formed by impressing

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A deformation pattern has been formed by impressing the jaws of a mechanical testing machine into the coarse grain surface of a recrystallized aluminum sheet metal. Finally, the sample surface was ground and mechani- cally polished such that the pattern was no longer visible. The stamp process, however, has changed the local texture. In the texture maps (Fig. 7.134), high pole densities can be recognized in regions where the corrugating teeth of the jaws caused a high deformation, while the grooves in the jaws induced a deformation low enough to preserve the original matrix texture. The texture maps of Fig. 7.134 were acquired simultaneously from the same sample area at symmetrical diffraction settings ( ϑ 1 = ϑ 2). Hence, the pole densities in the sample normal direction are shown. The matrix texture did not contribute to these selected diffraction peaks. If a texture component of the matrix is of interest, the specimen has to be tilted off the symmetrical geometry to an
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666 D. Rammlmair et al. (a) (b) Fig. 7.133. Gold pattern sputtered through a TEM support grid on a glass sub- strate. ( a ) Image in the light microscope. ( b ) X-ray micro-fluorescence map with the Au L α line 200 331 5 mm rel. intensity 9 8 7 6 5 4 3 2 1 0 Fig. 7.134. Texture maps of a deformation pattern in aluminum revealing local plastic deformation. Left: { 200 } reflections; right: { 331 } reflections
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Methodological Developments and Applications 667 111 200 220 Max. 3.4 Max. 3.9 Max. 3.1 P Fig. 7.135. Pole figures acquired across the rivet bolt of Fig. 7.136. The polar specimen direction P ( α = 35 , β = 83 ) has been used for texture and residual strain mapping appropriate pole-figure point. The corresponding angles of tilt can be read from X-ray pole figures that have to be acquired in advance. The X-ray spectrum (Fig. 7.132) contains two sets of characteristic lines: a set of Cu K α and Cu K β of scattered primary beam radiation (Cu anode, 40 keV), as well as a strong set of Mn K α and Mn K β fluorescence radiation, which has been emitted from the rather small content of manganese in the AlMn 1% alloy. Al–K fluorescence radiation, as a possible characteristic line from an Al sample, is not present. The Al–K fluorescent line is excited rather weakly by Cu K radiation and, furthermore, is strongly absorbed in air on the way from the sample to the EDS detector. In contrast to the sharp charac- teristic lines, the diffraction peaks are broad, due to the wide beam aperture (see (7.41)). In Fig. 7.132, the windows of the diffraction peaks (200), (220), (311)/(222), (400), (331), and (422) are marked by hatching. The (311) and (222) reflections are coincident, but the contribution of (222) is negligible in this particular point on the sample because the (111) peak is missing. A cross-section of an aluminum rivet was carefully polished flat by gen- tle mechanical grinding and finishing. A final electrochemical polishing was applied to remove any mechanical damage introduced during preparation. Be- fore mapping, several pole figures had been acquired in steps along lines across the head and the bolt of the rivet to recognize relevant texture components. A strong fiber texture has been found in the bolt region (Fig. 7.135) [473]. The
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  • Spring '14
  • MichaelDudley

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