Creep behavior of a novel Co-Al-W-base single crystal alloy containing Ta and Ti at 982 ∘C

The tensile creep behavior of a Co-Al-W-base single crystal alloy containing Ta and Ti was investigated at 982 ∘C and 248 MPa. The lattice misfit of experimental alloy was measured to be positive by synchrotron X-ray diffraction at high temperature, and long term heat treatment at 1000 ∘C for 1000 h revealed a γ′ volume fraction of 75% without secondary phases. The creep test indicated that the creep properties of experimental alloy exceeded commercial 1st generation Ni-base single crystal superalloy CMSX-3 with respect to the rupture life. The initial cuboidal γ′ precipitates directionally coarsened parallel to the applied stress axis during the creep process. The stacking faults in {111} planes within γ′ rafts were the primary creep deformation mode by TEM investigation.