Manifestation of the Portevin-Le Chatelier effect in the Kh20N80 alloy

It has been found that the single-phase nickel alloy Kh20N80 demonstrates discontinuous flow in the range of deformation temperatures of 300–650°C. It is shown that the discontinuous flow of this alloy possesses signs of the Portevin-Le Chatelier effect, strong localization of deformation, and negative strain-rate sensitivity of the flow stress. Furthermore, three specific features of the discontinuous flow of the Kh20N80 alloy have been revealed: (1) the “normal” dependence of the critical degrees of the onset of the discontinuous flow of ?_cr on the strain rate; (2) the “inverse” temperature dependence of ?_cr; and (3) the positive temperature dependence of the flow stress. These special features appear to be caused by the formation of a short-range-order structure, which occurs in this alloy at temperatures of approximately 350–500°C.