INFLUENCE OF TEMPERATURE AND STRAIN-RATE ON SLIP AND TWINNING BEHAVIOR OF ZR

The stress-strain behavior of pure Zr was studied systematically at va rious temperatures and strain rates. At 76 K, Zr deforms predominantly by twinning, whereas above room temperature (RT), slip is the control ling deformation mode. A transition in the rate-controlling deformatio n mode from slip to twinning has been observed to occur at intermediat e temperatures during the course of plastic deformation. Above 373 K, slip dominates the entire course of deformation. The transition from s lip to twinning in the stress-strain behavior is linked to differing s train-hardening rates and temperature sensitivities of the two deforma tion modes.