Theoretical study on the dislocation structure of parent–martensite interface in a magnetic shape memory alloy
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Ferromagnetic shape memory alloys have received increasing interest and have great potential for actuator and sensor applications, the mobility of the parent–martensite interphase interface in such alloys is determined by its interfacial structure and the migration mechanism; therefore, a thorough understanding of its nature is essential. In the present paper, the parent–martensite interface in a Ni2MnGa alloy is studied in the light of the topological model of martensite transformation crystallography, where the habit plane is envisaged comprising coherent terraces and steps. The coherency strains arising on the terrace plane are accommodated by a network of interfacial dislocations, e.g., twinning dislocations originating in the martensite phase, and disconnections. The topological parameters of these defects, i.e., the Burgers vectors, line directions, and dislocation spacings are quantified via rigorous crystallographic analysis and matrix algorithm based on the Frank-Bilby equation. Consequently, martensite transformation crystallographic features, e.g., the habit plane index and the orientation relationship, in the Ni2MnGa alloy are determined and found to be in good agreement with the results predicted by the well-established phenomenological theory.
KeywordsMartensite Burger Vector Martensite Phase Habit Plane Topological Model
The authors would like to thank Prof. R. C. Pond for valueable comments and suggestions. This research was supported by the National Natural Science Foundation of China under grant Nos. 50801029 and 50871039, and the Pearl River Young Scholar Program (2013J2200037) of the Science and Technology Projects of Guangzhou.
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