J. Phys. IV France 05 (1995) C2-245-C2-250
γ Precipitates in Cu-Zn-Al Alloys Studied by High Resolution Electron MicroscopyJ. Pons1, 2, 3
1 Lab. Métallurgie Structurale, ENSCP, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05, France
2 Centre d'Etudes de Chimie Métallurgique, CNRS, 15 rue G. Urbain, 94407 Vitry-sur-Seine, France
3 Dept. de Física, Universitat de les Illes Balears, ctra. de Valldemossa km 7,5, 07071 Palma de Mallorca, Spain
A HREM study of small γ-phase precipitates in β Cu-Zn-Al single crystals is presented. The images taken at atomic resolution show the perfect coherency of the precipitates when they are embedded in the β austenitic phase. In this case, the precipitates are located at the antiphase boundaries of the matrix. In turn, several microdomains separated by internal antiphase-like boundaries are present inside the precipitates. Nevertheless, the study of the boundaries at atomic level shows that the shift associated to the boundary (one atomic plane along <110>) is not a translations vector of the lattice. When the precipitates are embedded in a martensitic (18R) matrix, the precipitates loose the coherency. A mechanism of martensite/precipitate accommodation based on the formation of a small nanoplate at the interface between the main martensite plate and the precipitate, together with the formation of dislocations, has been observed.
© EDP Sciences 1995