Radiography in Modern Industry - Kodak

Figure 112: Powder diffraction patterns by the Debye-Scherrer-Hull method. Top: Sodiumchloride (common salt) (Na 2 Cl). Bottom: Sodium sulphate, anhydrous (Na 2 SO 4 ).Some indication of the size of the crystals of the powder can be derived from the character of thediffraction lines. The method also applies to the study of metallurgical samples in the form of foil,since these are, in general, polycrystalline. If the specimen is sufficiently transparent to the x-rays, the arrangement in Figure 109B in a previous figure may be used; but, if it is too thick, therays diffracted backward would be used, as in Figure 109C in the same figure. In this wayinformation is derived about mechanical strains and preferred orientations in the specimen, andabout the relation between these indications and the nature and amount of heat treatment or ofmechanical working.Films for X-ray DiffractionThe choice of a film for a particular problem depends on the radiation quality and the relativeimportance of film speed, contrast, and graininess.Since the parallax associated with an image on double-coated film may be objectionable incertain applications of x-ray diffraction, a single-coated film may be preferable. However, if adouble-coated film is used, one emulsion can be protected against the action of the developer bya waterproof tape, which is removed after the film is in the fixer. Alternatively the emulsion maybe removed from one side of the completely processed film. Methods of applying both thesetechniques are described in "Removal Of One Emulsion From Double-Coated Film".Often the location, rather than the intensity, of lines or spots of x-ray diffraction patterns is ofimportance. Under these circumstances, considerable savings in exposure time can be achievedby the chemical aftertreatment known as intensification, described in "Intensification OfUnderexposed Radiographs".X-ray Diffraction ReferencesAmoros, Jose L., Buerger, Martin J., And Amoros, Marisa C. - The Laue Method, AcademicPress, New York, San Francisco, London, 1975.Azaroff, Leonid V., And Buerger, Martin J. - The Powder Method In X-Ray Crystallography,Mcgraw-Hill Book Company, Inc., New York, 1958.Jeffery, J.W. - Methods In X-Ray Crystallography, Academic Press, London And New York, 1971.Klug, H. P., And Alexander, L E. - X-Ray Diffraction Procedures For Polycrystalline AndAmorphous Materials (2nd Ed), John Wiley And Sons, New York, 1974.Lipson, H., And Steeple, H. - Interpretation Of X-Ray Powder Diffraction Patterns, St. Martin'sPress, New York, 1970.Stout, George H., And Jensen, Lyle H. - X-Ray Structure Determination, The MacmillanCompany, New York, 1968.Radiography in Modern Industry 174