50%冷間圧延を施したAl-Mg-Si合金の焼鈍に伴う組織変化の同一視野観察
—その(1)再結晶粒の起源—

抄録

  Microstructural changes in an Al-Mg-Si alloy during annealing at 673 K after cold-rolling with a 50% reduction rate were observed. An alloy specimen was repeatedly subjected to intermittent annealing using a salt bath, Ar ion-polishing, and observation with SEM (Scanning Electron Microscope)-EBSD (Electron BackScatter Diffraction) system. The observations were carried out in the same view field on a specimen. Large lattice rotation occurred due to cold-rolling, which lead to formation of dislocation cells having orientations with broad range of angles, and made existing grain boundaries unclear. Strain induced grain boundary migration was not observed in this case. After annealing, the dislocation cells changed into subgrains surrounded by high and low angle boundaries, and some of them grew into recrystallized grains without change in orientation. These recrystallized grains (“crystallites”) originated from the dislocation cells in the deformed microstructure. The orientations of the crystallites were different from those of the surrounding subgrains.