Epitaxial relationship between dezincified layer (copper) and β′-brass as a matrix. Martensitic aspect

Abstract

During the spontaneous dissolution of β′-brass in oxidant-free solutions of sulphuric acid copper layers are formed. It was found that a relationship between the texture of the copper layers and orientation of big grains of β′-matrix is an inverse Kurdiumow-Sachs relationship: {111}Cu‖{110}β′; 〈110〉Cu‖〈111〉β′. The observed differences between the experimental and simulated pole figures are due to the fact that equal volume fraction of all 24 crystallographically-equivalent orientations was assumed in simulation. In an actual material, however, not all equivalent orientations are present, and participations of those which are present are not equal. The inverse Kurdiumow-Sachs relationship proves that zinc undergoes selective dissolution from β′-brass. The cubic primitive lattice of the remaining copper atoms changes into the cubic face-centred lattice of pure copper. This transformation is similar to non-diffusion martensitic transformation. Since this is a process occuring between the matrix and the copper layer being formed it therefore combines the elements of epitaxy and endotaxy which is why it can be named volume epitaxy.