The condition for the existence of a yield-drop in the stress-strain curves of crystals with an initially low dislocation density was derived. A new theory which differed greatly from the familiar Alexander-Haasen model was proposed for the description of the stressed state of a crystal near to the lower yield-point.

A Theory of Sharp Yield Point in Low-Dislocation Crystals. B.V.Petukhov: Technical Physics, 2001, 46[11], 1389-95