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

摘要

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 ℃ 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 ℃ to 800 ℃, 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 ℃, the deformation is dominated by dislocations shearing γ' particles. At 1000 ℃, the main deformation mechanism is dislocations bypassing γ' particles.