Polarization Curves of the Nickel-Base Alloys on a Single Tie-Line
Hideo Numata, Isao Tomizuka, Yutaka Koizumi
Polarization curves were measured for a series of superalloys whose compositions laid at 760°C on the γ/γ'-phase tie-line passing through the composition of René 95 and its extension into the γ'-phase region. The specimens were prepared by a powder metallurgy. The measurement was performed by a potentio-dynamic method in a 5N sulfuric acid. Most of the parameters derived from the curves had a maximum at a γ'-phase content of 70%. The Ecorr and the logarithm of the peak current density varied in accordance with a simple low of mixture. Some difference was observed between the heat-treated and the as-HIPed specimens likely due to the difference of the size of the γ'phases of the alloys.