The study of characteristics of the structure of metallic alloys using synchrotron radiation computed laminography (Research Review)

Abstract

The paper contains a review of research related to the use of synchrotron radiation computed laminography in the study of the structure features of metal alloys subjected to various methods of external action. Introduction. The important role of X-rays in the field of materials research is discussed. The capabilities of standard X-ray devices equipped with X-ray tubes and modern synchrotron radiation (SR) sources with unique parameters are compared. Methods for studying flat samples. Tomography and synchrotron laminography. An informative method based on the use of synchrotron X-rays is synchrotron radiation computed tomography (SRCT), which allows obtaining cross-section images of objects by processing multiple absorption radiographs. A brief classification of five generations of tomographs is presented. The problems encountered in obtaining data from non-compact (non-isometric) samples are avoided by using the method of synchrotron radiation computed laminography (SRCL), which combines the principles of laminography with the advantages of synchrotron imaging. Currently the method is used for non-destructive testing of non-isometric objects by a number of synchrotron radiation sources (ESRF, ANKA, Spring-8). Resolution of synchrotron radiation computed laminography. The use of monochromatic radiation in realization of computed laminography method is a factor, which provides high spatial resolution down to micron and submicron scale. An equally important factor is related to the characteristics of the detector. Images with a resolution of ~100 nm were obtained using nanolaminography. Comparison of laminography and tomography methods. Augmented laminography. Augmented laminography allows improving image quality by augmenting the Fourier space analyzed by laminography with information obtained from lower resolution CT. Reconstruction performed using Augmented laminography is characterized by the absence of significant artifacts and high resolution. Implementation of the laminography method. The angle of inclination of the rotary axis θ (SRCL method) is related to the geometry of samples and is determined experimentally in each case. In order to achieve the necessary resolution, the value θ should provide an optimal average value of the intensity of the passed radiation. The energy of X-rays is calculated on the basis of material characteristics. To reconstruct images of the objects, software complexes that implement the filtered back projection method based on the Radon transform are used. Examples of laminography application for analysis of metal alloys samples. The laminography method can be used for in-situ investigations allowing real time monitoring of processes occurring under different conditions of external action, e.g. during plastic deformation of metal plates. Data on formation of pore-type defects in the process of loading of metal workpieces are interesting. Numerous examples of post-mortem studies of metal alloys for various purposes are described in the literature. Important information is obtained in the study of fatigue cracks, as well as defects arising in the process of contact-fatigue loading of materials. Conclusion. The SRCT and SRCL methods are rationally implemented at the generation 4+ synchrotron radiation source “SKIF” under construction in Novosibirsk.