Study of phase composition of electrodeposited alloys of silver-cadmium system concerning some technological properties

The method of x-ray structural analysis was used in a phase composition study of electroprecipitated alloys of Ag-Cd system. Phases for the electroprecipitated alloys had an expanded range in comparison with the equilibrium phase diagram. Different phase composition could be obtained from alloys having identical chemical composition by varying conditions of the electrodeposition process. Different conditions for electrocrystallization of alloys with identical or similar phase composition result in different structural properties of electroprecipitated alloys and consequently in different physico-mechanical properties. An x-ray study of precipitated alloys containing 5,9 and 12% of cadmium shows the presence only of α-solid solution. However, the alloy containing 9% Cd is much harder than that containing 12% Cd. This is due to the presence in the lattice of the former of considerable elastic deformations (the Cd concentration in solid solution as determined by crystalline lattice period is almost twice higher than the real concentration). A significant difference in microhardness was observed in the case of precipitated alloys which had low or nearly identical cadmium concentration (up to 2%) and which according to the phase diagram should be homogeneous α-solid solution. X-ray structural analysis has showed that alloys are two-phase systems and together with the phase of pure or nearly pure silver (Lattice parameter 4.10-4.08 A) there is a phase with the BI-type lattice having parameters in the interval of 4.50-4.55 A. The second phase was determined to be solid solution of cadmium in cadmium oxide. To explain the origin of the CdO+Cd phase, the phase composition of freshly precipitated alloys was investigated