High Temperature Oxidation of a Series of Nickel-Base Superalloys on a Single Tye-Line and its Extension
Shizuo Nakazawa, Isao Tomizuka, Yutaka Koizumi, Akimitsu Miyazaki
An investigation was carried out on variation of oxidation behavior to be seen when the alloy compositions shift along a single tie line. The specimens were prepared from the alloys whose composition lay on the tie line of Rene-95 at 760°C or its extension. Oxidation was performed in oxygen at 1000, 1100 and 1200°C. A parabolic law was held for every alloy at 1200°C. A logarithmic law was held for every alloy but one at 1000°C. At 1100°C the behavior was parabolic for the alloys near to the γ-region and logarithmic for the alloys in or near to the γ'-region. The behavior of the intermediate region was near-parabolic in the first half, while it was near-logarithmic in the second. The reactivity generally decreased monotonously towards the γ'-region at all temperatures. The reactivity was, however, higher than the general trend for the alloys which were composed of two phases at the oxidation temperature as well as for the alloys within the γ'-phase region when the oxidation temperature was 1200°C.