scholarly journals Functional properties of NiTi nanofilm/Kapton composite

2022 ◽  
Vol 1213 (1) ◽  
pp. 012001
Author(s):  
A V Sibirev ◽  
M V Alchibaev ◽  
I A Palani ◽  
S Jayachandran ◽  
A Sahu ◽  
...  

Abstract The aim of the paper was to study the one-way and two-way shape memory effects in the NiTi nanofilm/Kapton composite. 500 nm film of the Ni50Ti50 alloy was deposited to Kapton by flash evaporation. After deposition, the NiTi layer was amorphous and the sample was held at a temperature of 350 - 400 °C for two hours in vacuum to crystallize the NiTi layer. As deposited sample as well as samples after heat treatment were bent around the mandrel with various diameters at room temperature and subjected to heating – cooling – heating through a temperature range of the martensitic transformations. It was shown that as-deposited sample did not demonstrate the recoverable stain variation. At the same time, the heat treated sample demonstrated the one-way shape memory effect on heating and a maximum recoverable strain was found to be 2 %. The two-way shape memory effect was not observed on further cooling and heating.

2016 ◽  
Vol 869 ◽  
pp. 474-478
Author(s):  
Luiz Carlos Sekitani da Silva ◽  
Cezar Henrique Gonzalez ◽  
Carlos Augusto do Nascimento Oliveira ◽  
Karla Carolina Alves da Silva

In the present work the copper base alloys with shape memory effects were characterized. The alloys were subjected to three different heat treatments that promoted changes in characteristics of thermoelastic martensitic transformation (transformation temperatures, thermal hysteresis and enthalpies of transformation). The alloys have their microstructures characterized by optical and scanning electron microscopy. Microhardness tests were performed. Differential scanning calorimetry (DSC) was used to evaluate the transformation critical temperatures of alloy and the transformation enthalpies for each heat treated sample. Thermoelastic properties have changed for each heat treatment. In the micrographs of the heat-treated samples was possible to observe the microstructure of the martensitic phase characteristic. They show the presence of martensite platelets (needles) self-accommodation.


2021 ◽  
Vol 11 (4) ◽  
pp. 1802
Author(s):  
Sneha Samal ◽  
Orsolya Molnárová ◽  
Filip Průša ◽  
Jaromír Kopeček ◽  
Luděk Heller ◽  
...  

An analysis of the shape memory effect of a NiTi alloy by using the spark plasma sintering approach has been carried out. Spark plasma sintering of Ti50Ni50 powder (20–63 µm) at a temperature of 900 °C produced specimens showing good shape memory effects. However, the sample showed 2.5% porosity due to a load of 48 MPa. Furthermore, an apparent shape memory effect was recorded and the specimens were characterized by uniformity in chemical composition and shape memory alloys of NiTi showed significant austenite phases with a bending strain recovery of >2.5%.


2008 ◽  
Vol 106 (6) ◽  
pp. 630-640 ◽  
Author(s):  
V. V. Sagaradze ◽  
V. I. Voronin ◽  
Yu. I. Filippov ◽  
V. A. Kazantsev ◽  
M. L. Mukhin ◽  
...  

1999 ◽  
Vol 596 ◽  
Author(s):  
W. Biegel ◽  
R. Klarmann ◽  
M. Kuhn ◽  
B. Wörz ◽  
B. Stritzker

AbstractPulsed Laser Deposition (PLD) was used to deposit La-doped Pb(Zr,Ti)O3 (PZT) thin films onto NiTi foils. The substrate alloy with composition Ni50Ti50 shows a strong shape memory effect with a transition temperature of about 80°C. This simple bicomponental system could have the potential of an actuator device (NiTi shows a strain up to 5 % during thermal cycling) with an inherent sensorial component (PZT) for the generated elongation. The deposited ceramic films were characterized with respect to their structural properties (XRD) and their ferroelectric behavior (P-E hysteresis). Under certain deposition conditions the growth of pure perovskite PZT on the polycrystalline shape memory alloy was observed. The growth morphology of PZT on NiTi was compared to the one of PZT on single crystalline substrates whereas no distinctive texture of the films on NiTi could be found. The ferroelectric behavior of the PZT films depend on the stage of bending of the film-substrate compound.


Author(s):  
A. N. Monogenov ◽  
V. E. Gyunter ◽  
E. S. Marchenko ◽  
S. G. Anikeev ◽  
V. N. Khodorenko ◽  
...  

2012 ◽  
Vol 570 ◽  
pp. 87-95 ◽  
Author(s):  
Irfan Haider Abidi ◽  
Fazal Ahmad Khalid

The combination of attractive properties of porous NiTi shape memory alloys like high recoverable strain due to superelasticity and shape memory effect, good corrosion resistance, improved biocompatibilty, low density and stiffness along with its porous structure similar to that of bone make them best materials for biomedical implants. In current study porous NiTi SMAs have been fabricated successfully by space holder technique via pressureless sintering using NaCl powder as a spacer. Various volume fractions of NaCl powders have been involved to study their effect on the pore characteristics as well as on mechanical properties of foam. Porous NiTi with average porosity in the range of 44.3%-63.5% have been fabricated having average pore size 419µm which were very appropriate for various biomedical implants. Porous NiTi SMAs exhibited superelasticity at room temperature and shape memory effect was also determined. Maximum recoverable strain of 6.79% was demonstrated by the porous NiTi alloy with 44.3% porosity and it was diminishing with increasing porosity. Compression strength and elastic modulus have shown a decreasing trend with increasing porosity content. Elastic modulus of porous NiTi extends from 1.38 to 5.42GPa depending upon the pore volume which was very much comparable to that of various kinds of bones.


2009 ◽  
Vol 283-286 ◽  
pp. 139-148
Author(s):  
Devendra Gupta ◽  
David S. Lieberman

The Au-Cd alloys continue to be important vehicles of research for the shape memory effect involving martensitic transformations and related phenomena.They transform to a variety of martensitic structures depending on the alloy composition and thermal history. Additionally, the Au-rich alloys display rubber like behavior involving thermo-elastic memory. Defects and diffusion play important roles in determining these properties. Defects and diffusion mechanisms in the Au- 47.5 - 50.5 at.% Cd alloys are examined. Diffusion in the nanometer regime and the states of defects are found to be important contributing factors to determine the shape memory effect, the variable martensitic transformations and the rubber like behavior, which are discussed in details.


Sign in / Sign up

Export Citation Format

Share Document