Mechanical Properties and Related Substructure of TiNi Shape Memory Alloys

¹ Institute of Materials Engineering, Technical University Ostrava, 70833 Ostrava, Poruba, Czech Republic
² Institute of Physical Metallurgy and Materials Testing, University of Leoben, 8700 Leoben, Austria

Abstract

The mechanical properties of binary near equiatomic TiNi shape memory alloys were investigated after different types of mechanical and heat treatments. The changes of deformation behaviour are explained on the basis of substructure differences after work hardening. The "elastic moduli" of both the high-temperature phase B2 and the martensite B19' as well as the "easy stage of deformation" are dependent on the work hardening intensity and these changes are related to the mobility of B2/B19' interfaces. The martensite changes its morphology after work hardening. In contrast to a twinned martensite, typical for annealed alloys, the internally slipped martensite was detected after work hardening.