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 degrees C at a constant strain rate of 1.0 x 10(-4) s(-1). The alloy exhibits comparable yield strength with that of Co-Al-W-base alloys containing more tungsten. From 600 degrees C to 800 degrees 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 gamma channels and gamma' 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 degrees C, the deformation is dominated by dislocations shearing gamma' particles. At 1000 degrees C, the main deformation mechanism is dislocations bypassing gamma' particles. (C) 2014 Elsevier B.V. All rights reserved.