Irradiation-induced migration of a [001] Σ = 5 tilt boundary was monitored by means of  in situ  high-resolution transmission electron microscopy, with a temporal resolution of 1/60s. The migration process was clarified for the first time. It was found that the non-periodic boundary, which was made up of several structural units, migrated and became a periodic structure along (310)A-(3¯10)B planes when the units transformed into ones which were surrounded by (310)A-(3¯10)B facets. The units which were surrounded by (120)A-(210)B facets grew and became aligned along the (120)A-(210)B planes. It was found that migration proceeded at every translation and transformation of 3 kinds of structural unit in the boundary, and that the migration speed was controlled by the time intervals required for translation or transformation of the units. It was shown that the atomic arrangement of the boundary during translation and transformation was predicted by the coincidence-site lattice model when the boundary was composed of stable structural units.

T.Kizuka, M.Iijima, N.Tanaka: Philosophical Magazine A, 1998, 77[2], 413-22