Quantification of Solid Solution Strengthening and Internal Stresses through Creep Testing of Ni-Containing Single Crystals at 980 °C

Various alloy compositions were cast as single crystals in a Bridgman vacuum induction furnace and creep tested at 980 °C: pure Ni, the equiatomic alloys CoCrNi CrMnFeCoNi (Cantor alloy), single-phase fcc (Ni) solid solution (with composition of matrix-phase CMSX-3 CMSX-4), two-phase Ni-based superalloys CMSX-4. Due to single-crystal state, grain size effects, boundary sliding, diffusion can be excluded. The results identify two major strengthening mechanisms: other mechanisms summarized precipitation hardening. Configurational entropy does not increase strength: Cantor alloy, with highest configurational all tested, shows weak similar strength °C comparison Ni zero entropy. element Re is very effective strengthener, both well superalloys. Quantitative estimations different internal back stress, misfit stresses, Orowan bowing, ??-phase cutting (in case superalloys) are presented. Finite simulations allow estimating influence matrix on behavior