Deformation and recrystallization of a channel die compressed aluminium bicrystal with (112) [11(1)over-bar]/(123) [41(2)over-bar] orientation

The development of microstructure and texture during deformation and recrystallization has been studied in a high-purity aluminium bicrystal with (112)[111]/(123)[412] orientation deformed 90% by compression in a channel die. The boundary plane of the bicrystal is located at the middle of the width, along the length of the crystals and inclined at 20° to the plane of compression. The microstructure is characterized over a wide scale by optical microscopy, SEM and TEM. The local orientation and misorientation are examined by EBSP in SEM and by microdiffraction and Kikuchi pattern analysis in TEM. The macrotexture is determined by X-ray diffraction. The deformation microstructure in both crystals is heterogeneous, particularly, shear bands with relatively large local misorientations form in the (112)[111] crystal. The orientation of the (112)[111] crystal is stable during deformation whereas the (123)[412] crystal changes to (011)[311]. The presence of the bicrystal boundary does not significantly affect the deformation microstructure and the boundary is not a strong nucleation site. Intragranular nucleation occurs in shear bands in the (112)[111] crystal and an approximate 〈111〉 rotation relationship exists between the orientation of the nuclei and the deformed matrix. The growth of these nuclei is fast and their crystallographic orientation dominates the recrystallization texture in the (112)[111] crystal.