J. Phys. IV France 112 (2003) 529
Martensitic transformations in shape-memory Cu-Zn-AI alloys with the -phase particles and the bainite crystalsI. Khomskaya, V. Zel'dovich and N. Frolova
Institute of Metal Physics, Ural Division, Russian Academy of Sciences, 18 S. Kovalevskaya St., 620219 Ekaterinburg, Russia
The martensitic transformations in Cu-Zn-A1 alloys undergoing the decomposition of solid solution with the formation of rod-like -phase or of plate-type bainite crystals have been studied by optical microscopy, electron microscopy and electron-probe microanalysis. The fine structure of the phases formed upon the partial decomposition of -phase and upon the subsequent martensitic transformation was studied. The transformation was shown to occur in a crystallographically ordered manner and to obey the Kurdyumov-Sachs orientation relationships. The transformation includes features of both diffusional and martensitic transformations. The -phase formation inclues a crystals lattice reconstruction and the nucleation dislocations in periodically arranged slip planes. At the same time, the shape of the -phase crystals and their coalescence and changes in chemical composition are typical of diffusional transformation. The interactions of martensite crystals with particles of the phase and bainite crystals were studied.
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