Strengthening of an L12-ordered γ′-intermetallic by disordered γ-particles. Part II: Measurements of the CRSS and TEM observations of dislocation processes in Ni69Co9Al18Ti4

Abstract Strengthening of single crystals of an L1 2 -long-range ordered γ′-phase by coherent disordered spherical f.c.c. γ-precipitates has been experimentally investigated. The overall composition of the material is (at.%): Ni 69, Co 9, Al 18, Ti 4. The critical resolved shear stress (CRSS) has been measured at 253 K for homogeneous, i.e. γ-free specimens and for specimens strengthened by three different γ-precipitate dispersions. The experimental results for the CRSS are in good agreement with those obtained by computer simulations (Part I) and are satisfactorily represented by Friedel's relation. The relevant configurations of dislocations have been studied by transmission electron microscopy.