Observation of the Habit-Plane Shift and the Morphology of alpha '' Nitride (Fe sub 16 N sub 2 ) Precipitate in alpha -Fe

摘要

The habit plane shift phenomenon of alpha '' nitride (Fe sub 16 N sub 2 ) precipitate in alpha -Fe is discovered by TEM observation. The habit plane of alpha '' precipitate shifts from (100) toward (102). The angular shift increases as the precipitate grows. Also, the angular shift increases as the aspect ratio of alpha '' particle increased. This relation has been predicted by considering the finite thickness effect on Khachaturyan's elastic theory. The crystal structure of the habit shifted precipitate is found to be distorted from a tetragonal structure, the structure of the initial alpha '' precipitate. The real morphology of alpha '' precipitate at the early stage is revealed as a rosette pattern on (001) habit plane. The branches of the rosette point in <100> and <110> directions. The possible reasons for the rosette morphology are discussed. (ERA citation 07:061794)