Abstract: A Re-containing Ni-base single crystal superalloy was used to investigate the elementary processes associated with stress-rupture behavior at different temperatures where the γʹ rafting occurs. At 900 °C, the rupture behavior is mainly determined by the multiplication of dislocations within the widening γ channels, which is closely linked with the propagation of microcracks along the inherent γ/γʹ interfaces. The rapid formation of lamella γ/γʹ raft structure, along with the developed-well interfacial dislocation networks, and its elastic instability are primarily responsible for the rupture behavior at 1100 °C. There is a clear curvature tendency in the Larson-Miller plot of stress-rupture lifetime in relation to stress at high temperatures. It indicates that the influence extent of γʹ rafting on stress-rupture behavior is sensitive to the acting conditions of temperature and stress.

Key words: Ni-based single crystal superalloy, Re effect, γʹ, rafting, Stress-rupture behavior, Elementary process, Larson-Miller plot