Abstract
Time-resolved X-ray tomography (4D-CT) and three-dimensional X-ray diffraction (3DXRD) were performed to investigate semisolid deformation in Al–10mass%Cu alloy. The configurations of solid grains were observed in-situ by 4D-CT and the crystallographic orientations of grains were also measured by 3DXRD. Translation and rotation of the solid grains in the semisolid are quantitatively analysed by the reconstructed 3D images and the diffraction spots. Based on the in-situ observation, we discuss about the motion of the solid grains and the formation of the shear band during the semisolid deformation.
Highlights
In various casting processes of metallic alloys, elimination of casting defects such as macrosegregation, porosity and hot tear is required for improving quality of castings and promoting efficiency of casting processes
This paper demonstrates the 3D grain motion in Al–10mass%Cu alloys with diameter of 1 mm during semisolid deformation by using the 4D-CT and 3DXRD technique developed by our group
Once deformation was applied to the specimen, the impingement between the solid grains and the rearrangement of the solid grains occurred, resulting in the formation of the shear band indicated as the white arrows in figure 3
Summary
In various casting processes of metallic alloys, elimination of casting defects such as macrosegregation, porosity and hot tear is required for improving quality of castings and promoting efficiency of casting processes. It is of interest to study semisolid deformation in metallic alloys because the semisolid deformation occurs in various casting processes and is closely related to the formation of casting defects. The semisolid processing and the centrifugal casting generate the stress which influences the semisolid microstructure [1–3]. In common with granular materials, the rheological behaviour such as dilatancy was found in semisolid alloys [1, 2], which provides apparent volume expansion in response to shear deformation. Various studies about the rheology of semisolid alloys such as the mechanical and viscus behaviours, and the deformation of solid grains, have been reported. The change in the microstructure during the semisolid deformation has not been fully understood, which is essential to understand the formation mechanism of casting defects
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