Influence of martensite fine structure on the shape memory effect in Fe-Ni alloys

The connection is established between the martensite fine structure in Fe-(20-30)wt % Ni alloys, the bending deflection value on cooling under load (lower than the yield limit) and the degree of the initial shape restoration at heating. The largest bending deflection was observed in the Fe-20wt % Ni alloy when the martensite with cell dislocation substructure was formed, and the maximum restoration degree - in the Fe-33wt % Ni alloy when the martensite with high density of fine twins appeared. That portion of bending deflection is restored at heating which is conditioned by macroscopic shear at direct transformation