Dai Pinqiang

Preferred orientation of grain boundary plane in recrystallized high purity aluminum

Compared with the research of preferred orientation of crystals (crystallographic texture) which started nearly a century ago, preferred orientation of grain boundary plane in polycrystalline materials is a lately proposed research direction with the development of five parameter analysis which is based on electron backscatter diffraction and stereological method. Systematic investigations into the preferred orientation of grain boundary plane and in-depth understanding on their evolution natures will be important to the manipulation of the microstructures of desired properties. In current paper, high purity aluminum (99.99 wt%) samples were cold rolled with 85% thickness reduction followed by a recrystallization annealing at 330℃ for 15-60 minutes and then the grain boundary plane orientations were studied. The results indicate there indeed exist preferred orientations of grain boundary planes in the recrystallized microstructure and the preferred orientation evolves sequentially from {2 2 3} to {1 1 1} and {1 0 0} planes during grain growth. Further discussion points out the recrystallization of high purity aluminum after cold rolling could be a so-called continuous recrystallization which involves sub-grain coalescence and sub-grain growing, and low angle grain boundary (mis- orientation angles ranging from 2° to 15°) constitutes the main part of the entire grain boundaries in the recrystallized microstructure. During grain growth, the crystallographic texture evolves from {1 1 0} (Brass) to {0 1 1} (Goss) and {0 2 3} co- existed, and low angle grain boundary planes usually orient on the exact position of low energy tilt boundaries due to the effects of crystallographic texture and crystallographic plane energy. This is the reason for the regular evolution of the preferred orientation of grain boundary planes as observed.