Anisotropic absorption of X-rays in polyphase materials

1990

X-ray diffraction in a lamellar two-phase material is considered. If the lamellae thicknesses are small compared with the penetration depth of the X-rays then the absorption factor depends on the whole path of incident and reflected beam in both phases. Particularly, it depends on a rotation γ about the diffraction vector s additional to the orientation (αβ) of this vector with respect to the sample. Numerical calculations of the absorption factor A(αβγ) have been carried out for different values of lamellae thicknesses D1D2, absorption coefficients μ1μ2 and lamellae orientations ωρ with respect to the sample surface.

Section: Introductionmentioning

confidence: 92%

Numerical Calculation of Anisotropic Absorption Factors for Lamellar Two‐Phase Structures

Liu

1990

“…shown as a function of the angle , of the diffraction plane relative to the lamellae plane (Bunge, Liu, Hanneforth, 1987 Figure 13 Anisotropic absorption of X-rays in lamellar structures, a) Metallographic section of a directionally solidified Pb-Sn eutectic b) Absorption factor as a function of the angle ), between lamellar plane and diffraction plane.…”

Section: Multiphase Materialsmentioning

confidence: 99%

Advantages of Neutron Diffraction in Texture Analysis

1989

Neutron diffraction texture analysis is based on pole figure measurement followed by pole figure inversion. Neutron diffraction pole figure measurement is quite similar to that by X-rays. There are, however, several advantages in detail which are mainly due to the lower absorption coefficient. Besides these quantitative differences, there is one principle difference between the two methods. Neutron diffraction allows the magnetic texture to be measured which is not possible by X-rays. The paper gives a survey on the advantages of neutron diffraction texture analysis which are only counteracted by the limited availability and higher costs of neutron diffraction.

“…It has also been found that the textures of the phases in multiphase composites may be strongly different from textures in single phase materials with the same degree of deformation (Wassermann, Bergmann, Frommeyer 1978). Furthermore, texture measurements by x-ray diffraction in multiphase materials may suffer from the effect of anisotropic absorption (Bunge, Liu, Hanneforth, 1987). Hence, quantitative texture measurements in deformed composites must be carried out by neutron diffraction (Brokmeier, B6cker, Bunge in print) which has not yet been done for the above mentioned Fe-Ag composites.…”

Section: Internal Stressesmentioning

confidence: 99%

Model Calculations of Elastic Moduli in Highly Deformed Composites

1989

Young's modulus of heavily deformed two-phase composites shows an unusually high increase after plastic deformation. It is assumed that this is due to two reasons, i.e. texture changes and changes of the moduli of the constitutive phases on the basis of non-linear elasticity theory and internal stresses of opposite sign in the phases. Expressions of the two contributions are given on the basis of simple model assumptions. It is estimated that the changes of shape and arrangement of the phases and shape and arrangement of the crystallites in the phases are only of minor importance.