AbstractFor determination of stress in a localized area, we combined a modified single exposure technique and the imaging plate, which is an x-ray digital area detector. With the, single exposure method, stress value is obtained from lattice strains in two directions with a single incident x-ray beam directed at an oblique angle. However, since diffraction data around a whole Debye-Scherrer ring was used in this study, a stress value can be accurately determined in comparison with the single exposure method. We observed the DS ring by use of the imaging plate with requiring only a short exposure time. Lattice strains in many directions on a DS ring were measured by an image analyzer connected to a computer; we verified the effectiveness of this method.
A high temperature stage was designed for mounting onto a computer controlled four
circle X-ray texture goniometer. This technique allowed to conduct in situ texture measurement,
i.e. the determination of the texture evolution during rather than subsequent to
annealing. The device was employed for temperatures up to 1000°C.The furnace consisted of a resistance wire of Pt30Rh, which was isolated against the
specimen with Al2O3 glue. The furnace with the specimen was covered by a hemispherical
KaptonTM foil. Inside the hemisphere a reducing gas atmosphere was used to avoid
oxidation of the sample surface.
As applied to tubes from Zr-based alloys, the X-ray method was developed to determine the dislocation density distribution in a-Zr depending on the orientation of Burgers vector. The method consists in registration of X-ray line profiles by each successive position of the sample in the course of diffractometric texture measurement using reflections of two orders, the following determination of coherent domain size and lattice distortion by means of the Warren-Averbach method for each orientation of reflecting planes, separate calculation of the density of c- and a-dislocations with all possible orientations of Burgers vector and presentation of results in generalized pole figures. Obtained data testify that the dislocation density varies within very wide intervals of several orders of magnitude depending on the grain orientation both in as-rolled and annealed tubes. Features of the constructed dislocation distributions are closely related to the crystallographic texture of studied tubes.
Measurement of shearing stresses, τxzand τyz, by X-ray diffraction technique with two-dimensional detector was studied. The principle which was developed for an area detector type X-ray triaxial stress analysis was adopted for this purpose. In the present method, Debye ring was measured first and its whole part was used for determining shearing stresses. One Debye ring is enough to determine shearing stresses without accurate diffraction data such as lattice spacing in stress free. The result of the simulation showed that the present method is useful for the evaluation of shearing stresses by X-ray diffraction technique.
A new method of calculating the crystal orientation matrix (Umatrix) of a specified sample using two-dimensional X-ray diffraction spots that are recorded on an area detector is presented. In this way, theUmatrix is calculated using at least three two-dimensional diffraction spots of known two-dimensional indices, which provide the projection of the crystal truncation rod onto the detector. The method, in the case of surface X-ray diffraction measurements with an area detector, enables easier and faster sample alignment than the conventional method to determine theUmatrix.
The diffraction anomalous fine structure (DAFS) method that is a spectroscopic analysis combined with resonant X-ray diffraction enables the determination of the valence state and local structure of a selected element at a specific crystalline site and/or phase. This method has been improved by using a polycrystalline sample, channel-cut monochromator optics with an undulator synchrotron radiation source, an area detector and direct determination of resonant terms with a logarithmic dispersion relation. This study makes the DAFS method more convenient and saves a large amount of measurement time in comparison with the conventional DAFS method with a single crystal. The improved DAFS method has been applied to some model samples, Ni foil and Fe3O4powder, to demonstrate the validity of the measurement and the analysis of the present DAFS method.
The method for grain size determination by statistical fluctuations of X-ray intensity, registered during measurement of texture pole figures, was developed. Niobium and bronze rods as well as tubes from Zr-1%Nb alloy, subjected to annealing at different temperatures, were studied. Description of the method, pole figures (PF), X-ray intensity distribution within PF circular sections, grain size values and their errors are presented.
Activation energies for the intermixing reaction of textured metal-metal multilayer thin films have been determined using X-ray diffraction analysis. Kinetic data were collected utilizing an area detector so as to reduce intensity bias from changes in out-of-plane texture during the intermixing reaction. Activation energies for Al/Pt, Ni/Ti, and Co/Al metal-metal multilayer thin films have been determined as 95.4(2) kJ/mol, 201(13) kJ/mol, and 247(19) kJ/mol, respectively.
With an X-ray area detector and a suitable Soller-plate collimator in the scattered radiation field, it is possible to realize a versatile X-ray diffractometer. The local diffraction information of a sample can be registered simultaneously and visualized with a spatial resolution better than 0.5 mm, maintaining reasonable measuring times of a few minutes. Results of measurements applied to local phase analysis (distribution of retained austenite and carbon on a cross section of case-hardened steel), to the determination of lateral stress distributions (laser-hardened track on C45 steel) and to the analysis of crystallite orientation (coarse-grained YBa2Cu3O
δ
) are presented.
High Temperature Texture Goniometer for in Situ Measurements of Transformation Textures