Simultaneous measurements of electrical resistivity and inelastic strain ac
cumulation in Ti-49.5 at.% Ni undergoing a two-step B2 --> R --> B19' marte
nsitic transformation were performed. To exclude the influence of specimen
size changes during the deformation all experiments were made in torsion. I
t was detected that noticeable part of strain recovery after heating under
a stress and active deformation in martensitic state rakes place before the
start of the reverse transformation and is obviously connected with twinni
ng. At the same time the two-way shape memory effects are caused by the mar
tensitic transformation. The obtained data may be useful for adequate model
ling of mechanical properties of the shape memory alloys because allow to c
onnect the macroscopic parameters with microscopic physical processes. (C)
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