Effect of thermomechanical treatment on deformational behavior of ferromagnetic Fe–Ni–Co–Ti alloy under uniaxial tension

Abstract

To improve the functional properties of a ferromagnetic shape memory alloy, a thermomechanical treatment that includes drawing followed by quenching and high-temperature annealing was proposed, as a result of which a nanostructured state is formed. Thermomechanical treatment (TMT) increases the alloy thermoelasticity, although it is accompanied by a large temperature hysteresis of martensitic transformation and results in a significant hardening of the matrix, which, in its turn, enlarges the effects of shape memory and superelasticity (or pseudoelasticity). It has been established that TMT of Fe–Ni–Co–Ti shape memory alloy contributes to an increase in reversible superelastic deformation up to ~ 3%. In a superelastic cycle with wide mechanical hysteresis, a large dissipation energy per loading–unloading cycle was gained, that favors the use of this alloy as a damper of mechanical oscillations.