FORMATION OF RECRYSTALLIZED GRAINS AT GRAIN-BOUNDARIES OF COPPER BICRYSTALS DEFORMED IN TENSION

In order to clarify the formation mechanisms of recrystallized grains along grain boundaries, 99.99 mass% copper bicrystals were prepared us ing the modified Bridgman method. They were deformed in tension to the strain of 30-40% and annealed at certain conditions to get the early stage of primary recrystallization along the grain boundaries. The for mation of recrystallized grains along the grain boundaries due to the strain induced boundary migration (SIBM) was observed, especially duri ng the in situ observation by TEM. The formation of recrystallized gra ins due to the SIBM occurred along the grain boundaries with a high ti lt component, toward which dislocations with large edge components pil ed up. The formation due to the [111] rotation mechanism occurred, on the other hand, along the grain boundaries with a high twist component , toward which dislocations with large screw components piled up. Duri ng the migration of the original grain boundaries many annealing twins were formed.