Due to this single-exposure measurement, changing the angle of incidence is no longer necessary, and a goniometer is no longer required in the XRD measurement device. Instead of using a zero or one-dimensional sensor, this technique utilizes a two-dimensional sensor to acquire the entire Debye-Scherrer ring simultaneously. The cosα (cosine alpha) XRD method is an improvement on the sin2 ψ (sin squared psi) method we discussed earlier. The Marion-Cohen method can be used to measure residual stresses within an object by characterizing the dependence of lattice spacing on stresses within highly textured materials.įor stresses produced by shot peening, machining, or grinding, residual stresses that are measured with the Marion-Cohen method produce nearly identical results when compared to the Two-Angle and sin2 ψ methods. Lattice spacing data is then determined by using two extreme values of ψ, typically 0 and 45 degrees. Just as the name suggests, the two-angle method is used to determine stress within a polycrystalline material by measuring the lattice spacing of any two ψ (psi) angles, as long as the lattice spacing is a linear function of sin2 ψ. Debye-Scherrer rings are the resulting concentric diffraction rings produced by Bragg reflections when a highly parallel electron beam illuminates polycrystalline grains within an object. Once a portion of the ring has been acquired, the incidence angle is changed to acquire the remaining crystal distortion data. To perform a measurement using sin2 ψ, a zero or one-dimensional sensor is used to acquire a portion of the diffraction Debye-Scherrer ring. The sin2 ψ method was initially developed in the 1920s and used for X-ray residual stress analysis for many decades this method is also still used by manufacturers today. These techniques include the Sin2 ψ method, the Two-Angle method, the Marion-Cohen method, and the cosα method. X-ray diffraction can be performed using various techniques depending on the application and the particular use case where it’s being implemented.
Pictured: The cosα XRD method XRD Techniques
0 kommentar(er)
