Tensile deformation and recrystallization of aluminum single crystals with sub-grained structures studied by synchrotron X-ray radiation

Abstract

X-ray diffraction experiments were carried out to non-destructively study the interior of aluminum single crystals at the pre-deformation, post-deformation and post-annealing stages using synchrotron radiation at SPring-8. Single crystals were grown by the Bridgman method. The as-grown samples were not perfect from the crystallographic perspective, but were composed of several sub-grains with misorientations smaller than 1° across the sub-boundaries. Although the difference in orientation in the cross section of the sample increased about 0.7° by the application of the nominal strain of 8% in tension along the <111> direction, the sub-grain structures remained largely unchanged. No evidence was found of the local accumulation of dislocations at the sub-boundaries. The orientation map of the deformed sample clearly shows that no non-uniformly deformed regions formed inside the sample. The level of residual strain calculated by the strain-scanning method was as low as 1×10-4. After annealing at 480 °C, the whole cross section of the center of the sample was covered by a single recrystallized grain. Although the resolution of the present experiments was insufficient to observe potential nucleation sites of recrystallized grains in <111>-oriented crystals, a possible candidate for the sites may be assumed at the intersections of certain types of slip bands.

Keywords

• aluminum
• single crystal
• sub-grain
• tensile deformation
• recrystallization
• synchrotron radiation