Structure and Thermal Stability of Tin-nickel Alloys Electrodeposited from Acid Baths

SummaryX-ray powder photographs of alloys deposited from three types of acid bath were examined. Wide variation in deposition conditions was needed to cause significant change in alloy composition. An alloy with 31 w/o nickel, or more, was a single phase, intermetallic compound whatever the bath used, and retained the same structure up to 43 w/o nickel, the highest value reached. Alloys with less than 31 w/o nickel were two phase mixtures. The single phase alloys increase in density and in compressive internal stress as the nickel content rises, but without major change of lattice parameters. All the single phase alloys decomposed at 300° C, including those whose composition falls within a single phase region of the nickel-tin equilibrium diagram. The single phase alloy is not, therefore, an extension of a cast phase outside the usual composition limits but a new compound.