AlおよびMg中における酸化物粒子と転位との相互作用の電顕観察

Abstract

Interaction between dislocations and oxide particles was observed with a transmission electron microscope. The specimens of aluminium and magnesium were prepared so that an array of oxide particles was introduced in the middle part of each specimen along the direction of the final rolling. After heat-treatment or heat-treatment and working, the specimens were thinned by electrolytic polishing and were set in an electron microscope. As the dislocations were moved by the emission of electron beam, microphotographs were taken intermittently. The results obtained are as follows: (1) Rapid cooling from annealing temperature resulted in the formation of small dislocation loops in aluminium matrix. There were, however, denuded zones of these loops in the vicinity of the array of particles as well as grain boundaries. There relatively long dislocations associated with particles were observed. In the case of magnesium specimens, the generation of dislocations from the interface of matrix and particles and consequently the formation of dislocation networks were observed. (2) Many dislocations in both specimens which were generated and moved by emission of electron beam, interacted with particles. In aluminium specimens, arrests of moving dislocations and cross slips were preferentially observed. In magnesium specimens, however, the formation of dislocation loops as well as arrest and bending of dislocations was observed. (3) According to the working degree, cell structures, especially in aluminium, were formed, an array of particles taking part in its formation. However, with increase in working degree there were no appreciable differences in the cell structures between the matrix and the vicinity of the array of particles. (4) Finally, some considerations were made on the decrease in critical shear stress required for dislocation to pass through particles dispersed non-uniformly.