Low-cycle fatigue of nickel superalloy single crystals at elevated temperatures

Single-crystal samples of nickel superalloys containing rhenium or rhenium plus ruthenium are subjected to low-cycle fatigue (LCF) tests under rigid cycle conditions at temperatures of 850 and 1050°C. It is found that the single crystals of the alloy containing rhenium with ruthenium have higher LCF resistance at 10⁴ cycles as compared to the alloy containing only rhenium. At a test temperature of 850°C, volume stress concentrators in the form of pores or their clusters represent fatigue crack nucleation zones; at 1050°C, surface corrosion cracks are the main fracture zones. The fatigue microcrack growth rate is anisotropic: it is higher in the 001] direction and lower in the 011] direction.