Effect of Temperature on the Low-Cycle Fatigue Characteristics of Single Crystals Made of an Ni3Al-Based Rhenium-Containing Intermetallic Alloy

-The low-cycle fatigue (LCF) of the single crystals made of a gamma'-Ni3Al-based VKNA-25 gamma' + gamma nickel superalloy is studied at 10(4) cycles and a temperature of 20, 750, and 900 degrees C. A temperature anomaly in the LCF fatigue limit of the VKNA alloy, namely, its increase with temperature in the range from 20 to 750 degrees C, is detected. This anomaly is related to a change from octahedral to cubic slip at the temperature of the peak in L1(2)-ordered alloys and to a change in the properties of the gamma' and gamma phases. At normal temperature, the static tensile strength and the LCF characteristics of the [111] single crystals are higher than those of the single crystals with other crystallographic orientations (CGOs). The static tensile strengths of the [001] and [111] single crystals at 900 degrees C and the strengths of the single crystals with all CGOs at 1000 degrees C are almost the same, and the LCF fatigue limit of the [001] single crystals at 900 degrees C is slightly higher than that of the [111] single crystals.