APPARENT MODULUS OF ELASTICITY OF NEAR-EQUIATOMIC NITI

Stress-to-strain differential values were measured in tensile testing at various stages of deformation in both austenitic and martensitic st ates of a near-equiatomic NiTi shape memory alloy as a measurement of the moduli of elasticity for the two phases. It was found that the mea surements varied with testing conditions, including strain and tempera ture. This observation indicates that the mechanical measurements are only the apparent modulus of elasticity, which is affected by contribu tions to the apparent elastic deformation from other deformation mecha nisms. These additional contributions to deformation are attributed to the stress-induced martensitic transformation and martensite reorient ation processes. (C) 1998 Elsevier Science S.A.