УДК 544.651.13: 544.621.22 Vladimir L. Krasikov1 , Aleksey V. Krasikov2 MECHANISM FOR INDUCED CODEPOSITION OF ALLOYS AND SOME SINGLE REFRACTORY METALS JSC Russian Institute of Radionavigation and Time RIRT, 120 Obukhovskoy Oborony pr., St. Petersburg, 192012, Russia Central Research Institute of Structural Materials “Prometey”, 49 Shpalernaya str., St. Petersburg, 191015, Russia e-mail: elchkras@yandex.ru It is shown that the new model of induced codeposition, based on experimental data for nickel-tungsten alloys electrodeposition from pyrophosphate electrolyte, may be applied for the explanation of electrodeposition regularities of other alloys of refractory metals as well as some single refractory metals, in particular, chromium and rhenium. <...> The reduction of refractory metals to the metal state is caused by the formation of cluster heterometal compounds with the direct chemical bond between refractory metal and inducing metal. <...> During chromium deposition, Cr (III) ions act as the inducing metal while Cr (VI) ions behave as refractory metal. <...> Any transition metal including electropositive ones may play the role of inducing metal. <...> The special role of small clusters of inducing metal in the formation of refractory metals alloys is also shown. <...> Keywords: induced codeposition, electrodeposition mechanism, nickel-tungsten alloy, chromium, rhenium, cluster heterometal compound, metal-metal bond, refractory metal, inducing metal DOI 10.15217/issn1998984-9.2016.37.8 The study of kinetics and mechanism of nickel and tungsten induced codeposition to the alloy obtained from the alkaline pyrophosphate electrolyte (using traditional experimental technique for recording potentiostatic polarization curves in hydrogen atmosphere) has shown, that the partial rate of tungsten reduction grows in direct proportion with increase in the concentration of both nickel and tungstate ions [1]. <...> At the same time, the partial rate of nickel reduction to the alloy is directly proportional to nickel and hydroxyl ions concentration, inversely proportional to pyrophosphate anions concentration and does not depend on tungstate concentration. <...> The carried out research allows us to make a conclusion that the tungsten reduction to metal is preceded through the stage of nickel ions Ni (II) reduction to intermediate particle NiOHads. ticle and tungstate in its initial form WO4 1 2 The subsequent chemical interaction of this par2- results in formation of heterometal cluster compound with nickel-tungsten <...>