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 1.0×10−4 s−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.