Abstract
INVESTIGATING the distribution of the intensity along the Laue spots from thick (6 mm.) deformed aluminium crystals, we have found that it depends strongly upon the degree of the plastic deformation. The spots from a thick undeformed crystal are elongated radially and uniformly black (Fig. 1). Each portion of the spot is formed by rays reflected from a corresponding region of the crystal along the beam. The spots from the same crystal only slightly plastically deformed (0.5 per cent) are no longer uniformly black (Fig. 2). The blackening increases on the ends of all spots and also in the inner parts of several spots. The spots become double or triple and similar to the multiple spots which have been described in other investigations1. This result indicates that the exterior layers, and certain layers situated inside, scatter more energy and therefore are more imperfect than other layers. We conclude that the degree of the plastic deformation and, therefore, the distribution of the residual stresses along the path of the beam are not uniform. The dependence of the doubling on the distance from the crystal to the photographic plate is an indication of the focusing property of the differently oriented blocks, situated along the path of the beam (the beam was one of small divergence). It seems that multiple Laue spots which have been described in previous investigations1 may be due to the reversible or irreversible changes of the perfection of the crystals and also to the focusing in the case of the deformed crystals.
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Y. Sakisaka and I. Sumoto, Proc. Phys.-Math. Soc. Japan, (3), 15, 211; 1931. C. S. Barret, Phys. Rev., 38, 832; 1931. I.-S. Cork, Phys. Rev., 42, 749; 1932.
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KOMAR, A., OBUKHOFF, W. Multiple Laue Spots from Aluminium Crystals. Nature 133, 687 (1934). https://doi.org/10.1038/133687a0
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DOI: https://doi.org/10.1038/133687a0
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