粉末冶金アルミニウム-2%鉄合金における[110]優先方位形成過程の電子顕微鏡観察

抄録

In order to study formation mechanism of the preferred orientation during annealing after swaging in the alloy prepared by extrusion of gas atomized powders, swaged and recovered structures as well as structure of recrystallization fronts were observed by transmission electron microscopies. The [110] oriented recrystallizing grains are found to originate from those cells in the deformed structure that contain high density Al-Fe compound particles. In the case of [110] oriented recrystallizing grains, their {111} planes are nearly parallel to {110} planes of the both [111] and [110] oriented matrix grains, making a wedge-shaped recrystallization front moving in the longitudinal direction. The specially oriented wedged-shaped front is free from particles, while any other recrystallization fronts are pinned down by particles either precipitating on themselves or precipitated in the recovered matrix. High resolution transmission electron micrographs suggest that the migration of the specially oriented interface normal to the interface plane proceeds by formation of {111} plane steps on the interface preceded by migration of grain boundary triple point and their following movement in the interface plane. The formation of the preferred orientation has been inferred to be associated with high mobility of the recrystallization front of the [110] oriented grains in the longitudinal direction in relation with the special structure of the front.