Creep behaviour of a novel CoNi-base single-crystal superalloy at high temperature and low stress

The tensile creep behaviour of a novel CoNi-base single-crystal superalloy was investigated at 1093 degrees C/62 MPa. The rupture life of this alloy reached 140 h, which was mainly attributed to a high fraction of gamma' phase. The interrupted creep test at 0.5% strain indicated that no rafting structure formed and gamma' phase remained a spherical morphology during creep, due to the small lattice misfit, 0.024% at 1093 degrees C. Shearing gamma' phase by multiple dislocations was the predominant substructure configuration in the steady-state stage, instead of planar defects which are commonly reported during relatively low-temperature creep of Co and CoNi-base single-crystal superalloys. (C) 2019 Elsevier B.V. All rights reserved.