Rate-dependent tensile deformation of twinned martensitic shape memory alloy was studied using strain rates as high as 300/s. The results showed that the stress plateau which was associated with martensite de-twinning still existed under high strain-rate deformation. The results suggested that de-twinning took place in the initial stages of tension deformation, and was not very sensitive to the strain rate within the range (0.001 to 300/s) studied. Beyond the stress-plateau region, where dislocation mechanisms were expected to dominate the deformation processes, the stress level increased more strongly with increasing strain rate. The transformation characteristics and shape-recovery processes in dynamically deformed samples provided further evidence that de-twinning was well-developed in this alloy under dynamic tension deformation.

Rate Dependence of Deformation Mechanisms in a Shape Memory Alloy. Y.Liu, Y.Li, K.T.Ramesh: Philosophical Magazine A, 2002, 82[12], 2461-73. See also: Philosophical Magazine Letters, 2002, 82[9], 511-7