In-situ Phase Analysis of Large Inclusions By Combining Computed Tomography And Energy-selective X-ray Diffraction

Abstract

The accurate positions of large inclusions in bulk metal can be determined using a computed tomography system but phase information for these inclusions cannot be obtained by the computed tomography method. In-situ phase information for internal material could be non-destructively obtained by an energy-selective diffraction system; however, it is necessary to place the inclusion in the centre of the diffraction area to ensure that the obtained diffraction signal comes from the inclusion material rather than the base material, which is difficult without appropriate non-destructive testing methods. In-situ phase information for large inclusions in the bulk metal could, in principle, be obtained by combining computed tomography and energy-selective X-ray diffraction (ESXRD) in one instrument. In this research, an X-ray analysis device with this capability is built. The computed tomography system and the energy-selective diffraction system share the same tungsten target X-ray source, motion system and spatial coordinates. A simulated sample containing inclusions is fabricated with a diameter of 20 mm and a height of 20 mm. The base material of the simulated sample is aluminium and the inclusions are α-Al2 O3 ceramic spheres with diameters of 1.5 mm, 2.5 mm, 3.5 mm and 5 mm. The diffraction information of some inclusions embedded in the simulated sample is successfully obtained using the combination instrument and the factors affecting the diffraction signal of the inclusions are analysed.