Electrochemical Phase Formation of Metals and Alloys at Chemically Identical Solid or Liquid Cathode: Part 2. Alloys in the Form of Substitutional Solid Solutions

Electrochemical Polymorphic Phase Formation in Metals

“…The last two years were marked by new experimental results proving the existence of the phenomenon of the electrochemical phase formation in metals and alloys via a supercooled liquid state stage. Relying on the data obtained, it was found that the discussed phenomenon is proved by the following experimental facts: -(1) electrochemical phase formation in metals resulting in phases with amorphous structure typical of a solidified metallic liquid when crystallization is hindered in the course of deposition [28]; -(2) the formation enhancement of intermetallic compounds involving metallic cathode elements and the electrodepositing metal plus evolvement of additional intermetallics enriched in cathode elements, on replacing a solid cathode with a chemically identical liquid one [29]; -(3) the formation of intermetallics between solid metallic cathode elements and the solvent in the alloy electrodepositing as substitution solid solution, as well as enhancement of these processes accompanied by the development of additional intermetallics enriched in cathode elements on replacing a solid cathode with a chemically identical liquid one [30]; -(4) with alloys electrodepositing as substitution solid solution at a solid metallic cathode, the formation of intermetallics including cathode elements and the alloy solute element building no distinct phase [30]; -(5) on replacing a solid cathode with a chemically identical liquid one, intermetallics formation is enhanced involving metallic cathode elements and the electrodepositing alloy solute, building no distinct phase, plus additional intermetallics enriched in cathode elements emerge [30]; -(6) with alloys electrodepositing as intermetallic compounds at a solid metallic cathode, formation of intermetallics involv-ing components of the depositing alloy and, in parallel, cathode elements and alloy components is observed [31]; - (7) on replacing a solid cathode with a chemically identical liquid one for alloys electrodepositing as intermetallic compounds, additional intermetallics enriched in the major alloy component and cathode elements are formed [31]. The aim of the work was the further experimental verification of the existence of the phenomenon in point.…”

Review—Electrochemical Phase Formation via a Supercooled Liquid State Stage: Metastable Structures and Intermediate Phases

“…(2) intermetallics development involving this or that solid cathode element and a solute in the electrodepositing alloy building no distinct phase; and (3) enhancement of the two processes accompanied by emergence of additional intermetallics enriched in cathode elements when a solid cathode is replaced with a chemically identical liquid one. 174 The anticipated effects are based on several well-known facts. The diffusion coefficient of a liquid metal is several times that of a solid one because the atoms of a liquid metal are in an excited state.…”

“…In this case, additional intermetallics will be enriched in elements of the metallic cathode. 174 On the contrary, if the intermetallics development during electrochemical phase formation in alloys is assumed not to involve a liquid phase, then the time space of their development must exceed the electrodeposition time by many orders of magnitude. For example, the formation of intermetallics by supersaturated solid solution decomposition requires a special thermal treatment like aging or tempering whose major parameters are maintaining time and temperature.…”

“…A conclusive evidence for the phenomenon at hand will be the formation of intermetallics involving a solid metal cathode element and an alloy solute building no distinct phase in the alloy because an intermetallic can in this case develop only due to crystallization of some metallic liquid. 174 The experimentation involved a copper-bearing nickel alloy Ni (Cu) and a silver-bearing copper alloy Cu(Ag). These were selected first of all because the phase formation in them follows Hume-Rothery rules, the atomic radius difference in the pair nickel-copper being at 3% and in copper-silver at 12%.…”

“…The fact that solid cathode elements tin and cadmium interact with nickel and copper, the elements of the electrodepositing alloy, is the evidence that a liquid state stage is present in the process of the alloy electrochemical phase formation. 174 The occurrence of the intermetallic Cu 2 Cd composed of cadmium, an element contained in the solid Wood's metal electrode, and copper, the solute building no distinct phase in the electrodepositing alloy Ni(Cu) (Fig. 19a), is a conclusive evidence for the phenomenon in point.…”