Affiliations: [a] Georgian Technical University, 77 Kostava str, 380077
Tbilisi, Georgia. Tel./Fax: +995 332932; E-mail: mszgc@access.sanet.ge
| [b] Scandinavian Memory Metals AB, Stockholm, Saltsjobaden
13321, Box 72, Sweden | [c] Saint-Petersburg University, Saint Petersburg
Abstract: The degree of recoverable strain, reactive stress and
pseudoelasticity of some Ti-Ta-Zr alloys were investigated. The measurement
technique involved differential calorimetry, estimation of friction and
evaluation of recoverable torsion strain. The alloys were quenched from
different temperatures of the β-phase area and subjected to additional
thermal and mechanical treatment required for subsequent examination. The
degree of recoverable strain was measured on custom-made unit. The samples have
been heated by electrical current and using a furnace. Initial deformation of
the specimens was achieved by torsion. For all of the alloys the shape recovery
was not less than 90–98% for initial strain up to 7–9%.
M_{s} and A_{s} values for the alloys
range in 298–433 K and 523–673 K interval. These allowed to
conventionally consider the shape memory effect in these alloys as a "high
temperature" (respectively to TiNi) phenomenon. The values of the reactive
stress induced by reverse martensite transformation in the alloys was measured
to be 300–550 MPa. After 3–4 cycles the pseudoelasticity of the
alloys (strain-stress cycled at room temperature), for the initial strain
– 3.5–4%, comes up to 100%.
