摘要
用透射电子显微镜就位观察了镍钛合金的马氏体相变和预马氏体相变。发现存在反向记忆的变态单元,它形成的过程可以分为三个阶段: (1)用应变时效相Ni_4Ti_3和位错线来标志和划定单元的界线; (2)弯折分布的R相构成变态单元的界墙; (3)单变态的马氏体充填变态单元的领域。同时对相变晶体学作了讨论。
In-situ electron microscopy observations of the martensitic and premarten-sitic transformations in thin foil of equiatomic TiNi alloys have been made. i The variant unit was found to be involved in the reversible memory behavio-ur. The orientation relationships between matrix parent phase, cubic precipi-tate Ni_4 Ti_3 phase, in termediate rhombohedral phase and monoclinic martensite-phase were anew determined, and their matrix xpression formulas were also deduced from obtained diffraction patterns. The forming process of the shapememory unit was divided into three stages as following sequence:(1) The delimitation of the unit boundary line by constrain-aging precipitate X phase and associated dislocations. (2) The unit walls constructing of the zigzag thombohedral phases.
(3) The parallel extension of the rhombohedral phases and martensiticgrowing to be fill in shape memory unit range.
