抄録
Thermal expansion properties of Invar (Fe-36 mass%Ni) alloy electrodeposits were investigated. The Fe-36 mass%Ni alloy electrodeposits from sulfate/chloride electrolytes using additives, saccharin sodium, and malonic acid. The electrodeposits, of about 150 μm thickness, had no crack. The thermal expansion curve showed that contraction of the electrodeposits occurred in the 270-420 °C range during first heating. During the first cooling and second heating, it showed the same behavior as that of melted Invar alloy. The coefficient of thermal expansion α (CTE) exhibited approximately α = 10×10−6/°C for the as-deposited electrodeposits and approximately α = 1×10−6/°C for electrodeposits annealed above 500°C. The CTEs of the electrodeposits annealed above 500 °C showed excellent agreement with that of the melted Invar alloy. The decrease in the CTE resulted from the increase of the fcc phase in the electrodeposits caused by heat treatment.
Invar alloy electrodeposits are anticipated for application to high-definition electroformed products with low CTEs.
