Dependence of X-ray elastic constants of alumina on the diffraction plane.

Abstract

The dependence of the x-ray elastic constants on the diffraction plate was investigated by using seven kinds of diffraction planes of α-alumina with chromium, cobalt and copper Kα radiations. The stress applied to a specimen with a bending device was measured by x-rays using the Gaussian curve method. No difference larger than the confidence intervals was observed in the measured x-ray elastic constants. The relative error σK/K of the stress constant K is proportional to K which is proportional to cotθ. Therefore, it is important to choose the diffraction angel 2θ as close to 180° as possible in order to determine the stress and the stress constant precisely. The (410) plane measured with cobalt Kα radiation is most suitable for stress determination because it not only has the highest diffraction angle of 168.4° but also the measured x-ray elastic constants almost agreed with both values calculated from Reuss and Voigt models for the elastic deformation of polycrystalline materials.