Speaker
Description
X-ray diffraction (XRD) is a versatile non-destructive analytical technique used to analyze crystalline properties of various materials. This technique requires collimated monochromatic X-ray beam that reflects at certain angles from the crystals within the sample. The reflection angles are specific for given crystal type and its orientation. A composition of materials containing multiple crystalline phases can be analyzed this way. XRD analysis is an important tool for metallurgy, as crystalline microstructure directly affects the mechanical properties of alloys used in industry.
Current XRD systems utilize relatively low-energy monochromatic X-ray beam (5-20 keV) which can only penetrate shallow layer close to the sample surface. Therefore, the thick metallic parts cannot be analyzed through their entire volume. The only option is to use the synchrotron sources, which are not practical for industrial applications.
In this contribution we evaluate performance of the fast energy dispersive XRD system with polychromatic X-ray beam and spectrally sensitive imaging detector Timepix3. The results of pilot measurement demonstrate ability to sense the controlled recrystallization within volume of the 1.5 mm thick steel plate.
During the experiment the temperature of the sample changed from 25 to 750°C and back within five minutes, while its crystalline composition was monitored by dynamic XRD measurement. The sample was transmitted by a polychromatic collimated X-ray beam generated by a tungsten X-ray tube operating at 90 kV. The fully spectral imaging data recorded behind the sample by Timepix3 detector captured diffraction patterns corresponding to the actual microstructure of the sample. A comprehensive mathematical model describing the response of the experimental system was created. By comparing the model predictions with measured data, it was possible to perform data analysis with unexpectedly high precision. The timeline of dynamically changing ratio between the two significant crystalline phases of the steel (ferrite and austenite) was measured with standard deviation of 0.7%.
The experiment shows that it is possible to observe and possibly even control the metallurgic processes thanks to the novel technology of the spectrally sensitive imaging detectors.
| Workshop topics | Applications |
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