The Synergetic Effect of Rhenium and Ruthenium on the Long-Term Creep Strength of Single Crystals of Third- and Fourth-Generation Nickel-Based Superalloys

Comparative long-term creep tests of [001] single crystals of third-generation rhenium-containing nickel-based superalloy VZhM1 and fourth generation rhenium- and ruthenium-containing nickel-based superalloy VZhM4 were performed at temperatures of 850, 1000, 1100, and 1150°C for durations up to ~3000 h. It has been established that the alloys are equally strong at a temperature of 850°C. At higher temperatures of 1000, 1100, and 1150°C the curves of long-term creep strength \(\sigma = f\left( \tau \right)\) of the alloys intersect each other: at shorter times the creep strength of the VZhM1 alloy is higher than that of the VZhM4 alloy, while at longer times we have the inversion of creep strength. The time at which the long-term strength curves intersect each other shifts towards the lower values as the temperature increases and corresponds to the duration of incubation period of precipitation of topologically close-packed (TCP) phases in the structure of the VZhM1 alloy. Under similar test conditions, the volume fraction of TCP phases in the structure of the VZhM1 alloy is considerably larger than that in the VZhM4 alloy.