Abstract: The transformation hysteresis and stability of strain martensite in Ni_(47)Ti_(44)Nb_ alloy have been studied by means of tensile tests at various temperatures and electrical resistance measurements as well as TEM observations.It was shown that there is a characteristic deformation temperature and a strain range,in which the critical yield stress for stress-in- duced transformation acquires optimum matching with the yield strength of the β-Nb parti- cles.In this case,deformatian can effectively increase the transformation hysteresis,while the strain recovery ratio remains usefully high.The martensite with irreguldar fine.twin substructure and martensite containing some dislocations as well as martensite intersected by the β-Nb particles possess high stability.

Key words: NiTiNb shape memory alloy, transformation hysteresis, strain martensite