1991 年 32 巻 4 号 p. 325-330
A variant structure of bct martensite in Fe–Pd alloys was examined by transmission electron microscopy. The martensite variants constructing a colony which were transformed in a single crystal of austenite consisted of four kinds of variants belonging to a same “plane-group”. On the other hand, the variants which were transformed from recrystallized austenite with annealing twins were composed two kinds of them belonging to a same plane group and two of their mirror symmetrical ones about the annealing twin plane. The variants formed at the annealing twins had a common [011]b direction which was nearly normal to a (111)f austenite annealing twin plane.
Shape deformation matrices of the variants and the coherency at the interfaces of neighboring variants were calculated by Wechsler, Lieberman and Read’s phenomenological theory. The results indicated that control factors of the selection of variants of the colony were not only a magnitude of total shape deformation but also the coherency at variant interfaces. Annealing twins play a role of the nucleation sites of new martensite plates and reduces the number of kinds of variants from 24 to 6 by the formation of variant interfaces at the twin plane.
