A. N. Titenko, Institute of Magnetism, Kiev, Ukraine
Under certain conditions, alloys with thermoelastic martensite exhibit superelastic properties. The necessury conditions for the realization of superelastic deformation are a small volume effect DV/V of the martensitic transformation (MT), the presence of a shear strain component, and a high yield strength ss of matrix phase.
Two polycrystalline Fe-Ni-Co-Ti-Cu alloys, namely Fe-15,2Ni-37,0Co-8,0Ti-6,17Cu, Fe-15,2Ni-36,6Co-6,72Ti-7,62Cu (wt.%) were investigated. The MT temperatures were determined from the temperature dependences of the electrical resistance r(T) and low-field magnetic susceptibility c(T). The influence of austenite ferromagnetism on the volume change DV/V at the starting temperature Ms of forward a«g MT was studied using dilatometric technique. Small elasticity modulus of the austenite below Curie temperature Tc is favoured superelastic behaviour of investigated alloys. The superelastic characteristics are affected also by the duration of austenite annealing and deformation temperature.
Summary: Two polycrystalline Fe-Ni-Co-Ti-Cu alloys, namely Fe-15,2Ni-37,0Co-8,0Ti-6,17Cu, Fe-15,2Ni-36,6Co-6,72Ti-7,62Cu (wt.%) were investigated. The MT temperatures were determined from the temperature dependences of the electrical resistance r(T) and low-field magnetic susceptibility c(T). The influence of austenite ferromagnetism on the volume change DV/V at the starting temperature Ms of forward a�g MT was studied using dilatometric technique. Small elasticity modulus of the austenite below Curie temperature Tc is favoured superelastic behaviour of investigated alloys. The superelastic characteristics are affected also by the duration of austenite annealing and deformation temperature.
