Comparison of different dislocation representations of the yield strength of a monocrystal

Abstract

Two approaches to the determination of the yield strength of a monocrystal are analyzed, the dynamic which treats it as a point on the hardening curve at which the strain rate of the specimen or the dislocation velocity in it reaches a certain definite quantity, and the static in which the yield strength is a characteristic point of the distribution function of dislocation sources in the actuation stresses. Strain curves are compiled for LiF monocrystals obtained by different method, by active deformation, by step loading under creep conditions, and by modeling for a specific kind of slip band source. It is shown that the available dynamic approach has no single description of the whole multistage hardening curve for the monocrystal, and does not indicate a sufficient criterion for the yield strength while the static approach provides such a possibility.