Martensite Phases in Cu–Zn Metastable Alloys with the Shape Memory Effect

The martensitic transformations in Cu–38Zn and Cu–39.5Zn (wt %) alloys with the shape memory effect have been studied using a combination of transmission and scanning electron microscopy, optical metallography, and X-ray diffraction analysis. When examining specimen upon cooling to low temperatures in the transmission electron microscope column, the features of martensite morphology and fine structure, as well as of electron microdiffraction in the alloys, have been ascetained. The structural types of martensite phases \(\beta _{2}^{'}\) (3R) and \(\gamma _{2}^{'}\) (2H) have been identified in Cu–38Zn alloys, as well as \(\beta _{2}^{''}\) (9R) and \(\gamma _{2}^{'}\) (2H), in Cu–39.5Zn alloys. The proposed crystallographic models of martensitic rearrangement in the alloys are based on an analysis of X-ray and electron diffraction, including diffuse electron scattering, as well as on the packing defects of the internal substructure of martensite.