| Morphology, surface relief, and phase interface structure of {259}f, {225}f, {557}f and {3,10,15}f martensite as well as the effect of parent phase deformation on transformation in iron-based alloy, by means of Optical Microscope., Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM) and Transmission Electron Microscope (TEM) were intensively investigated in this paper.It's shown that the formation and growth of {3,10,15}f martensite completely depended on self-accommodation of variants which made the habit plane of martensite become invariant plane, and parent phase only did elasticity coordination, with the course of growth, the crystal orientation between martensite and austenite retained the N-W relation.{259}t martensite with medium ridge grew from the medium ridge to two sides as well as kept the demutation mechanism , and the crystal relation between martensite and austenite nearly kept G-T relation .{225}f martensite without medium ridge was made up of lots of sub-plate martensites , and twin concentrated on one side of interface . During the course of growth towards another side, lots of parent phase plastic coordination was needed that the crystal orientation between martensite and austenite deviated , and the habit plane didn't retain the invariant plane. The formation and growth of {557}fmartensite with the substructure of dislocation completely depended on parent phase plastic coordination, and the habit plane rotated.Surface relief of (3,10,15}f, {259}f, {225}fand {557}f martensite was quantitatively observed and analysed by AFM. {3,10,15}f martensite surface relief with regular interface and definite similarity was -shaped , and two sides of surface relief were very flat . {259}f martensite surface relief which arrayed like bullet was "N"-shaped , and two tilted sides of surface relief were approximatively flat. {225}f martensite surface rielf which was made up of lots of little surface reliefs (or units) was "N"-shaped , but one side is flat and the other is undulated. {557}f martensite surface relief cluster was formed by surface relief "packets", and "packet" was further formed by several single surface relives. That surface relief "packets" was irregular "N"-shaped and its single surface relief was tent-shaped indicated that surface relief of{557}f martensite wasn't formed by homogeneous deformation and not to be IPS-type.Pre-deformation of parent phase had quite an effect on martensite and its surface relief morphology of {259}f and no effect on them of {557}f, {225}f. with the increase of pre-deformation stretch, {259}f martensite morphology changed slender as well as itsboundary from flat to curved. Correspondingly, the morphology of its surface relief turned kinked. With the increase of pre-deformation compression, martensite plate changed from thin and long shaped to lenticular shaped, as well as its boundary from flat to curved. Correspondingly, the morphology of its surface relief turned from long-plate shaped to short-plate shaped, as well as its boundary from flat to banded.It's shown that the probability to form perron on the (111) fplane with the common lattice dislocation for {3,10,15}f martensite was the biggest. Phase interface dislocation for {557} f martensite originated from mismating dislocation on the (111) fplane, and was different of common lattice dislocation from invariant shear. The perron structure at martensite interface was the result of semi-common lattice dynamics constraint. According to the K-S relation, when {225}finartensite was transforming , it existed two shares in some place of austenite, the relult turned (111) f plane into (110)m plane and turned (ll2) into The reason of it was that the dislocation with b1 and b2 vector respectively sheared the (111) f and (ll2Jf plane. For {225}f martensite, the direction of motion was mainly along the b2 vector in the (ll2) plane, however, the direction of motion was mainly along the b1 vector in the{lll}f plane for {557}f martensite.
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