Study of Imperfections of Crystal Structure in Polycrystalline Materials: Low Carbon Alloy and Silicon Ferrite

Abstract

The technique of the new x-ray double spectrometer method as described in a former paper1 is applied to the study of angular misalignment of crystal structure in alloys. To obtain a better statistical evaluation of the x-ray intensity data the method is extended to include arrays of spots on the Debye-Scherrer lines at high elevations. A complete mathematical discussion of the photometric transformation of the crystallite rocking curves is presented. The specimens investigated include a low carbon alloy annealed at 850°C and three silicon ferrite samples annealed at 980°, 1100°, and 1200°C. The quantitative data obtained disclose a significant dependence of crystal perfection on annealing temperature, and demonstrate clearly that the angular misalignment of the coherently reflecting regions within the grains decreases with annealing temperature provided this temperature is not excessive. Valuable information regarding the influence of cold rolling on the subsequent annealing process is obtained. Thus, the extent of partial recrystallization of the silicon ferrite is deduced from the statistical data, and the differential grain size between the surface layers and the interior of the specimen is revealed through the study of the diffraction effects with radiation of different wavelengths. A mechanism of grain bending during plastic deformation is suggested and a relationship between magnetic properties, annealing temperature, and crystal perfection of the silicon ferrite is pointed out.