On Functional Behavior of Strain-Aged Ti-Ni Alloy

2008 ◽  
Vol 59 ◽  
pp. 162-167 ◽  
Author(s):  
Elena P. Ryklina ◽  
Sergey Prokoshkin ◽  
A.A. Chernavina ◽  
Natasha N. Perevoshchikova
Keyword(s):  
Shape Memory ◽  
Thermomechanical Treatment ◽  
Functional Properties ◽  
Shape Recovery ◽  
Critical Temperatures ◽  
Functional Behavior ◽  
Bending Mode ◽  
Ni Alloy ◽  
External Training ◽  
Loading Modes

The functional properties of the Shape Memory Alloys (SMA): critical temperatures, recovery strain, shape recovery rate, two-way shape memory effect (TWSME) value, residual strain etc are determined by an alloy structure which is effectively regulated by thermomechanical treatment. External training parameters strongly affect the final properties as well. The main of them are as follows: strain and loading modes, loading temperature regime (phase state under deformation), load value, loading time, number of training cycles. Actual technical and medical SME articles are functioning on bending mode in most cases. Nevertheless, the influence of external training parameters under bending on properties was not systematically studied. The present work relates to study the combined influence of structure realized under various Low- Temperature Thermomechanical Treatment (LTMT) regimes, including isothermal annealing (strain aging), and external training parameters under bending on functional properties of Ti- 50.7at.%Ni alloy. Variation of training parameters enables additional regulation of final functional properties. The obtained results can be used for development elements functioning in conditions of TWSME realization.

A Comparative Study of Structure Formation in Thermomechanically Treated Ti-Ni and Ti-Nb-(Zr, Ta) SMA

2012 ◽  
Vol 706-709 ◽  
pp. 1931-1936 ◽  
Author(s):  
Sergey Prokoshkin ◽  
Vladimir Brailovski ◽  
Karine Inaekyan ◽  
Andrey Korotitskiy ◽  
Sergey Dubinskiy ◽  
...  
Keyword(s):  
Cold Rolling ◽  
Comparative Study ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Structure Formation ◽  
Thermomechanical Treatment ◽  
Functional Properties ◽  
Nanocrystalline Structure ◽  
Technological Factors

The processes of structure formation in Ti-Ni and in Ti-Nb-Zr, Ti-Nb-Ta shape memory alloys (SMA) under thermomechanical treatment (TMT) were studied. The TMT comprised cold rolling with true strains from e=0.25 to 2 and post-deformation annealing. Differences in these processes between two groups of alloys are considered. The main conclusions are as follows: nanostructures created by TMT are useful for radical improvement of the SMA functional properties, and an optimum nanostructure (nanocrystalline structure, nanosubgrained structure or theirmixture) should be selected by taking into account other structural and technological factors.

Creation of Substructure and Nanostructure in Thermomechanical Treatment and Control of Functional Properties of Ti - Ni Alloys with Shape Memory Effect

2005 ◽  
Vol 47 (5-6) ◽  
pp. 182-187 ◽  
Author(s):  
S. D. Prokoshkin ◽  
V. Brailovskii ◽  
I. Yu. Khmelevskaya ◽  
S. V. Dobatkin ◽  
K. E. Inaekyan ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Thermomechanical Treatment ◽  
Memory Effect ◽  
Functional Properties ◽  
Ni Alloys ◽  
And Control

Functional Properties of Ti-Ni-Based Shape Memory Alloys

2008 ◽  
Vol 59 ◽  
pp. 156-161 ◽  
Author(s):  
I. Khmelevskaya ◽  
Sergey Prokoshkin ◽  
Vladimir Brailovski ◽  
K.E. Inaekyan ◽  
Vincent Demers ◽  
...  
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Functional Properties ◽  
High Pressure Torsion ◽  
Martensitic Transformations ◽  
Critical Temperatures ◽  
Recoverable Strain ◽  
Ultrafine Grained

The main functional properties (FP) of Ti-Ni Shape Memory Alloys (SMA) are their critical temperatures of martensitic transformations, their maximum completely recoverable strain (er,1 max) and maximum recovery stress (sr max). Control of the Ti-Ni-based SMA FP develops by forming well-developed dislocation substructures or ultrafine-grained structures using various modes of thermomechanical treatment (TMT), including severe plastic deformation (SPD). The present work shows that TMT, including SPD, under conditions of high pressure torsion (HPT), equal-channel angular pressing (ECAP) or severe cold rolling followed by post-deformation annealing (PDA), which creates nanocrystalline or submicrocrystalline structures, is more beneficial from SMA FP point of view than does traditional TMT creating well-developed dislocation substructure. ECAP and low-temperature TMT by cold rolling followed by PDA allows formation of submicrocrystalline or nanocrystalline structures with grain size from 20 to 300 nm in bulk, and long-size samples of Ti-50.0; 50.6; 50.7%Ni and Ti-47%Ni-3%Fe alloys. The best combination of FP: sr max =1400 MPa and er,1 max=8%, is reached in Ti-Ni SMA after LTMT with e=1.9 followed by annealing at 400°C which results in nanocrystalline (grain size of 50 to 80 nm) structure formation. Application of ultrafine-grained SMA results in decrease in metal consumption for various medical implants and devices based on shape memory and superelastiсity effects.

Shape Memory Effect in Co-Ni Polycrystalline Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 2029-2032 ◽  
Author(s):  
Wei Min Zhou ◽  
Yan Liu ◽  
Bohong Jiang ◽  
Xuan Qi
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Recoverable Strain ◽  
Ni Alloys ◽  
Ni Content ◽  
Polycrystalline Alloys ◽  
Ni Alloy

Co-Ni alloys exhibit g(fcc)®e(hcp) martensitic transformation and show reversible induced strain under applied magnetic field, which means they are potential magneto-shape-memory materials. Polystalline of Co-Ni alloys with varied Ni content were prepared. The g(fcc)®e(hcp) martensitic transformation and shape memory effect (SME) of Co-Ni alloy were studied. The influences of Ni content and deformation temperature on SME were discussed. The shape recovery rate and recoverable strain decrease with the increase of Ni content.

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