The authors investigated the mechanical properties of Ni-58mass%Fe alloy electrodeposits, which are expected to be used as low thermal expansion materials, before and after heat treatment for one hour at 400 to 600°C. For the Ni-58mass%Fe alloy electrodeposits without heat treatment, ultimate tensile strength (UTS) was 1610MPa, elongation (&delta) was 7%, and hardness was 430HV. After heat treatment for one hour at 400, 500, and 600°C to stabilize the liner expansion coefficient of the Ni-58mass%Fe alloy electrodeposits, the alloy electrodeposits had a UTS of 830MPa, a &delta of 9%, and a hardness of 270HV at 400°C ; a UTS of 720MPa , a &delta of 17%, and a hardness of 240HV at 500°C ; and a UTS of 640MPa, a &delta of 22%, and a hardness of 220HV at 600°C. After heat treatment for one hour at 400 to 600°C, the mechanical properties of the Ni-58mass%Fe alloy electrodeposits were comparable to those of melted Ni-58mass%Fe alloys for IC leadframes. Though a reduction in the ductility of the Ni-58mass%Fe alloy electrodeposits after heat treatment for one hour at 400 to 600°C by grain boundary segregation of sulfur was expected because the alloy electrodeposits contained 0.04mass% sulfur, ductility of the alloy electrodeposits was not reduced after heat treatment in this temperature range. It was considered that since sulfur dispersed as granular Fe-Ni-S compounds in the Ni-58mass%Fe alloy electrodeposits after heat treatment for one hour at 400 to 600°C, embrittlement originating from sulfur segregation to grain boundaries of the alloy electrodeposits was able to be prevented.
The authors investigated deopsits of Zn-Ni alloys from a ZnCl2-NiCl2-EMIC ambient-temperature molten salt bath with various organic solvents added. It was found that the organic solvents had an effect on the surface morphology of alloys and the deposition conditions. The electrodeposit, which had a smooth, glossy, and crack-free surface, was obtained at low current density using ethylene glycol as a solvent. In addition, a smoother, denser, and more uniform deposition was performed by agitation applying gas bubbling. A crack-free and smooth amorphous Zn-Ni deposit was obtained under the conditions of 80°C, 2.0mA ⋅ cm–2, and 1.0mol% NiCl2 content in a bath with gas bubbling.