SHAPE MEMORY EFFECT IN THE SOME Ti-Ta-Zr ALLOYS

Tengiz Peradze 1Iuri Stamateli 1Jan Cederstrom 2Teimuraz Berikashvili 1Aleksandr Razov 3Kahaber Gorgadze 1

1. Georgian Technical University, Tbilisi, Georgia
2. Stokholm, Skandinavian Memory Metals AB, Sweden
3. Sankt-Peterburg University, Russian Federation

Abstract

The character of phase transformation due to the heating of alloys, the degree of recoverable strains reactive stresses, matrensite transformations (MT) dumping ability and pseudoelasticity of some Ti-Ta-Zr alloys were inverstigated and measured by differential calorimetry, internal friction measurements and evaluation of recoverable torsion strain.
The alloys speciments were quenched from different temperatures of β-phase (BCC) existence area and then subjected to additial different termo and mechanical actions necessury for the following measurements.
The degree of recoverable strains was measured on a self-assembled fram. The heating was performed by an electrical current through the specimens and by furnace. The initial deformation of the specimens was carred out by torsion.
For all the alloys the shape recovery was not less than 90-98% for initial strains up to 7-9%. The magnitudes of Ms and As for the alloys ranges in 250-400C interval.
So the shape memory effect is in the alloys may be conventionally named as a “high temperature” (respectively to TiNi).
The highest dumping ability was estimated in 44Ti-50Ta-6Zr alloy and that was equal to 23%. The values of the reactive stresses due to the reverse MT in the alloys was measured as 300-350 MPa. The dimension of pseudoelasticiti of the alloys (strain-stress cycled at a room temperature) comes up to 100% after 3-4 cycles for the initial strain ~3,5-4%.
Work was carry out by ISTC Project #G-499.

 

Presentation: poster at E-MRS Fall Meeting 2005, Symposium C, by Tengiz Peradze
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-27 10:40
Revised:   2009-06-07 00:44