Onset mechanisms of discontinuous flow at low temperatures in one- and two-phase CuBe alloys

Abstract

This paper presents the results of thorough experiments on discontinuous flow (DF) at low temperatures in the age-hardenable f.c.c. alloy CuBe 2 designed to check the controversial theories on this topic: the thermomechanical models (TMI) of Kubin and Estrin and the model of Obst et al. which asserts that only mechanical processes are responsible for the onset of DF. The TMI models are modified for surface heat transfer coefficients, which depend on the deformation-induced increase in temperature by a power law. The results suggest a thermal onset mechanism since the TMI models describe the experimental onset stresses appropriately, provided that heat transfer and slip localization are suitably accounted for.