Al-Mg合金粒界転位バーガース・ベクトルの電顕像シミュレーションによる判定

抄録

Burgers vector of a boundary dislocation in a recrystallized Al-Mg alloy was identified by comparing the transmission electron micrographs with two-beam dynamical theory computations.
A large angle goniometer stage was used to observe the specimen from various directions and the crystal orientations were determined by matching the diffraction pattern with the computed Kikuchi map on a graphic display. The image comparison showed that the particular dislocation is one of the b₃-type Burgers vectors whose magnitude is especially large. The direction and the spacing of the dislocation agreed with those of the dislocation network that can cause the measured misorientation from that of the perfect Σ33 coincidence. The calculation indicated that two more arrays of boundary dislocations of small Burgers vectors are in the boundary.
It is concluded that the dislocation array is only occasionally seen in the boundary of a polycrystalline specimen not because the array is absent but because the image is invisible in the micrograph.