Temperature dependence of low cycle fatigue for the Co-based single crystal superalloy

Abstract

The low cycle fatigue behaviors of the Co-Al-W-Ti-Ta single crystal superalloy were systematically investigated from room temperature to 900 °C. With the increase of temperature, the main slip mode gradually changes from planar slip of stacking faults in both γ and γ′ to wavy slip of dislocations in γ, which has rarely been reported in previous work. The deformation mechanism transition can not only be attributed to the disappearance of stacking faults in γ but also the decrease of critical stress for stacking faults to shear γ′ phase, which induced the density and type of stacking faults to change. In consequence, the deformation homogeneity in γ/γ′ decreased with the increase of temperature and more strain was localized in γ. The finding provides us a new idea on high performance single-crystal superalloy design.