C on the thermal cyclic response of the 49.8 Ni–42.2 Ti–8Hf (in at.%) high temperature
shape memory alloy was investigated. The improved thermal cyclic stability under constant
tensile stresses in the ECAEd samples was attributed to the increase in critical shear stress
levels for dislocation slip, which would accompany the martensitic phase transformation, due
to the microstructural refinement and increase in favorable dislocation density.