Design for anomalous yield in γ′-strengthening superalloys

Anomalous yield is a critical characteristic of temperature-resisted superalloys. However, it is undesirably anisotropic, being absent sometimes in the [111] crystallographic orientation. Here the orientation dependence of the yield behavior and the corresponding mechanism have been investigated. We show how the orientation affects the dislocations' motion in the γ-γ′ structure, where overcoming the critical resolved shear stress associated with anti-phase boundary plays a significant role. The influence of the orientation on anomalous yield is rationalized, and the criterion for the onset or absence of yield anomaly is proposed. An alloy design is then provided to effectively enhance yield strength anomaly. [Display omitted] •Anomalous yield is onset in [001]- and [011]-orientated superalloys but sometimes absent via [111] orientation.•Inhibiting γ'-shearing process, evidenced by {001} fracture surface and dislocation-free γ'-phases, causes such absence.•Overcoming the critical resolved shear stress associated with anti-phase boundary facilitates yield anomaly.•An effective approach to enhance temperature resistance is proposed and a resulting alloy has remarkable yield anomaly.