Microstructure and texture development in a polycrystal and different aluminium single crystals subjected to hydrostatic extrusion

[摘要] A hydrostatic extrusion (HE) process was applied to commercial pure polycrystalline aluminium (99.9%) and two aluminium single crystals $\langle$111$\rangle$ and $\langle$110$\rangle$. On comparison, the results obtained from single crystals and polycrystalline aggregates are unique. Microstructure and crystallographic texture investigations were performed by transmission electron microscopy, electron backscatter diffraction and X-ray diffraction (XRD). Significant differences in grain refinement and texture formation were noticed depending on the starting orientation. The deformed single crystal with $\langle$110$\rangle$ starting orientation features an average grain size value of 150% higher than the second investigated single crystal (0.5 μm forthe $\langle$111$\rangle$ single crystal and 1.3 $\mu$m for the second crystal). In turn, the average grain size obtained for polycrystalline aluminium is 0.9 $\mu$m. The deformation process causes a difference in the grain sizes, while a fraction of the high angle grain boundaries have a comparable volume percentage in all the deformed microstructures—reached about 35%. The qualitative and quantitative XRD texture results proved that the HE process leads to the formation of a characteristic fibrous texture.

[学科分类] 材料工程

[关键词] Deformation texture;crystallographic orientation;single crystal;electron backscattering diffraction;aluminium.