Superalloy single crystals are highly alloyed metallic systems, which are designed with the objective to realize a γ/γ’-microstructure with a high volume fraction (e.g. 70%) of cuboidal γ’-particles (L12-phase, average cube edge length: 0.3 µm) separated by thin γ-channels (fcc crystal structure, typical average channel width: 80 nm). However, other phases like the σ-phase can form under certain conditions. In the present study we use SEM and TEM to explore whether temperature cycling under stress promotes the formation of σ-phase. Emphasis is also placed on whether temperature cycling affects the kinetics of high temperature oxidation.