Temperature dependence of deformation behavior in a Co–Al–W-base single crystal superalloy

Tensile properties of a single-crystal Co–Al–W–Ni–Cr–Ta alloy with low tungsten content have been studied within the temperatures ranging from 20 to 1000°C at a constant strain rate of 1.0×10−4s−1. The alloy exhibits comparable yield strength with that of Co–Al–W-base alloys containing more tungsten. From 600°C to 800°C, a yield strength anomaly is observed, probably due to the cross-slip of superdislocations from the octahedral plane to the cube plane. TEM analysis demonstrates that stacking faults (SFs) appear both in γ channels and γ′ precipitates in a wide temperature range. These SFs are responsible for the obvious strain hardening observed in stress–strain curves. From room temperature to 900°C, the deformation is dominated by dislocations shearing γ′ particles. At 1000°C, the main deformation mechanism is dislocations bypassing γ′ particles.