Influence of the Particle Size on Phase Transformation Temperatures of Ni-49at.%Ti Shape Memory Alloy Powders

2010 ◽  
Vol 660-661 ◽  
pp. 124-127
Author(s):  
George Carlos S. Anselmo ◽  
Walman Benício de Castro ◽  
Carlos José de Araújo
Keyword(s):  
Particle Size ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Particle Sizes ◽  
Gas Atomization ◽  
Scanning Calorimetry ◽  
Transformation Temperatures ◽  
Ni Alloys ◽  
Material Saving ◽  
Start Temperature

It is important to control the martensitic transformation start temperature (Ms) of Ti–Ni alloys because it determines the temperature range over which the shape memory effect and superelasticity appear. Powder metallurgy (PM) is known to provide the possibility of material-saving and automated fabrication of at least semi-finished products as well as net-shape components for NiTi alloys. In this study powder with different particle sizes was subjected by gas atomization. The evolution of the control the martensitic transformation start temperature (Ms) was studied by differential scanning calorimetry. The effect of the particle size of powders on the transformation temperatures behaviors was discussed.

Effects of Magnetic Field and Hydrostatic Pressure on Martensitic Transformations in Some Shape Memory Alloys

1996 ◽  
Vol 459 ◽  
Author(s):  
T. Kakcshita ◽  
T. Saburi ◽  
K. Shimizu
Keyword(s):  
Magnetic Field ◽  
Hydrostatic Pressure ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Transformation Temperature ◽  
Isothermal Holding ◽  
Ti Alloy ◽  
Ni Alloys ◽  
The Magnetic Field ◽  
Start Temperature

ABSTRACTThe recent works carried by the author's group on the effects of magnetic field and hydrostatic pressure on martensitic transformation are reviewed, which mainly concerned with some shape memory allovs, such as Fe-Pt, Fe-Co-Ni-Ti, Ti-Ni and Cu-Al-Ni alloys. The works clarify the effects of magnetic field and hydrostatic pressure on martensitic transformation temperature, magnetoelastic martensitic transformation and morphology and arrangement of martensites and transformation process of athermal transformation. That is, transformation start temperatures in Fe-Pt and Fe-Ni alloys examined increase with increasing magnetic field, but are not affected in Ti-Ni and Cu-Al-Ni alloys. On the other hand, transformation start temperature decreases with increasing hydrostatic pressure in the Fe-Ni-Co-Ti alloy, but increases in Cu-Al-Ni alloys. The magnetic field and hydrostatic pressure dependences of the martensitic start temperature are in good agreement with those calculated by the equations proposed by our group. In the work on the ausaged Fe-Ni-Co-Ti alloy, the appearance of magnetoelastic martensitic transformation is newly found. In addition, several martensite plates grow nearly parallel to the direction of applied magnetic field in the specimen of an Fe-Ni alloy single crystal. Moreover, we found that in the Cu-Al-Ni alloys exhibiting an athermal martensitic transformation, isothermal holding at a temperature above Ms makes martensitic transformation to start and the incubation time increases with increasing ΔT = T − Ms (T represents holding temperature). The above results show that the magnetic field and hydrostatic pressure effectively control not only the transformation temperature but also the morphology and distribution of martensites induced, as in the case of uniaxtial stress and compression.

Shape Memory Behavior of NiMnGa/Epoxy Smart Composites

2005 ◽  
Vol 475-479 ◽  
pp. 2067-2070 ◽  
Author(s):  
Hideki Hosoda ◽  
Shinsuke Takeuchi ◽  
Tomonari Inamura ◽  
Kenji Wakashima ◽  
Shuichi Miyazaki
Keyword(s):  
Particle Size ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Cooling Rate ◽  
Applied Stress ◽  
Powder Size ◽  
Transformation Temperatures ◽  
Shape Memory Behavior ◽  
Smart Composites ◽  
Shape Memory Properties

A new type of smart composite developed in our group was studied in terms of shape memory behavior. The smart composites were composed of NiMnGa ferromagnetic shape memory alloy particles (FSMAP) and a polymer matrix, where NiMnGa FSMAP will bring shape memory effect and the matrix polymer enhances ductility. Two kinds of NiMnGa were selected by taking the phase constitution into account (parent or martensite state at room temperature). The shape memory properties are reported in terms of transformation temperature, powder size, applied stress and heating/cooling rate. It was found that martensitic transformation temperatures of the smart composites obtained by differential scanning calorimetry (DSC) were almost equal to those of NiMnGa FSMAPs. The shape recovery of the composites was confirmed in the strain-temperature curves obtained by dynamic mechanical analysis. Clear shape change was recognized corresponding to the martensitic transformation temperatures. The shape memory properties depend on heating/cooling rate, particle size and applied stress. Lower heating/cooling rate and smaller particle size brings better shape memory properties. This is because thermal conductivity of polymer is low and the amount of defects such as pores introduced during curing decreases with decreasing particle size. The improvement of processing is needed to reduce material defects.

scholarly journals Effect of Nd Addition on the Microstructure and Martensitic Transformation of Ni-Ti Shape Memory Alloys

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
M. Dovchinvanchig ◽  
C. W. Zhao ◽  
S. L. Zhao ◽  
X. K. Meng ◽  
Y. J. Jin ◽  
...  
Keyword(s):  
Rare Earth ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Earth Element ◽  
Transformation Behavior ◽  
Nd Addition ◽  
One Step ◽  
Niti Matrix ◽  
Start Temperature

The effect of rare earth element Nd addition on the microstructure and martensitic transformation behavior of Ni50Ti50−xNdx(x=0, 1, 3, 7, 20) shape memory alloy was investigated experimentally. The results showed that the microstructure of Ni-Ti-Nd ternary alloy consists of the NiNd phase and the NiTi matrix. One-step martensitic transformation was observed in all alloys. The martensitic transformation start temperatureMsincreased gradually with increasing Nd content for Ni-Ti-Nd alloys.

scholarly journals Microstructure and Phase Transformation Analysis of Ni50−xTi50Lax Shape Memory Alloys

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 345 ◽  
Author(s):  
Weiya Li ◽  
Chunwang Zhao
Keyword(s):  
Phase Transformation ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensite Transformation ◽  
Transformation Behavior ◽  
Ni Content ◽  
Start Temperature

The microstructure and martensitic transformation behavior of Ni50−xTi50Lax (x = 0.1, 0.3, 0.5, 0.7) shape memory alloys were investigated experimentally. Results show that the microstructure of Ni50−xTi50Lax alloys consists of a near-equiatomic TiNi matrix, LaNi precipitates, and Ti2Ni precipitates. With increasing La content, the amounts of LaNi and Ti2Ni precipitates demonstrate an increasing tendency. The martensitic transformation start temperature increases gradually with increasing La content. The Ni content is mainly responsible for the change in martensite transformation behavior in Ni50−xTi50Lax alloys.

Effect of Electroplastic Deformation on Martensitic Transformation in Coarse Grained and Ultrafine Grained Ni-Ti Shape Memory Alloy

2008 ◽  
Vol 584-586 ◽  
pp. 127-132 ◽  
Author(s):  
Anastasia E. Sergeeva ◽  
Daria Setman ◽  
Michael Zehetbauer ◽  
Sergey Prokoshkin ◽  
Vladimir V. Stolyarov
Keyword(s):  
Differential Scanning Calorimetry ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Cold Rolling ◽  
Shape Memory ◽  
Coarse Grained ◽  
Scanning Calorimetry ◽  
Structure Relaxation ◽  
Differential Scanning Calorimetry Method ◽  
Ultrafine Grained

The aim of this paper is the investigation of electroplastic deformation (EPD) and subsequent annealing influence on martensitic transformation in the shape memory Ni50.7Ti49.3 alloy. Using differential scanning calorimetry method it was shown that EPD at the low strain stimulates structure relaxation and recovers martensitic transformation in cooling, which is usually suppressed by cold rolling.

scholarly journals The Evaluation of Meloxicam Nanocrystals by Oral Administration with Different Particle Sizes

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 421
Author(s):  
Yao Yu ◽  
Yang Tian ◽  
Hui Zhang ◽  
Qingxian Jia ◽  
Xuejun Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Water Solubility ◽  
Cell Model ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Laser Scattering ◽  
Transport Studies ◽  
Transmission Electron ◽  
Transmission And Absorption

Meloxicam (MLX) is a non-steroidal anti-inflammatory drug used to treat rheumatoid arthritis and osteoarthritis. However, its poor water solubility limits the dissolution process and influences absorption. In order to solve this problem and improve its bioavailability, we prepared it in nanocrystals with three different particle sizes to improve solubility and compare the differences between various particle sizes. The nanocrystal particle sizes were studied through dynamic light scattering (DLS) and laser scattering (LS). Transmission electron microscopy (TEM) was used to characterize the morphology of nanocrystals. The sizes of meloxicam-nanocrystals-A (MLX-NCs-A), meloxicam-nanocrystals-B (MLX-NCs-B), and meloxicam-nanocrystals-C (MLX-NCs-C) were 3.262 ± 0.016 μm, 460.2 ± 9.5 nm, and 204.9 ± 2.8 nm, respectively. Molecular simulation was used to explore the distribution and interaction energy of MLX molecules and stabilizer molecules in water. The results of differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) proved that the crystalline state did not change in the preparation process. Transport studies of the Caco-2 cell model indicated that the cumulative degree of transport would increase as the particle size decreased. Additionally, plasma concentration–time curves showed that the AUC0–∞ of MLX-NCs-C were 3.58- and 2.92-fold greater than those of MLX-NCs-A and MLX-NCs-B, respectively. These results indicate that preparing MLX in nanocrystals can effectively improve the bioavailability, and the particle size of nanocrystals is an important factor in transmission and absorption.

scholarly journals The Nature of the β→α″ Transformation in Ti-Nb Alloys

2020 ◽  
Vol 321 ◽  
pp. 11052
Author(s):  
E.M. Hildyard ◽  
L.D. Connor ◽  
N. Martin ◽  
D. Rugg ◽  
H.J. Stone ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Stress Level ◽  
Total Stress ◽  
Synchrotron Diffraction ◽  
New Approach ◽  
Transformation Behaviour ◽  
Shape Memory Behaviour ◽  
Start Temperature

The martensitic transformation in Ti-Nb alloys can result in superelastic and shape memory behaviour but significant discrepancies exist between the transformation conditions reported for a given composition. To elucidate the reasons for these variations, in situ synchrotron diffraction experiments have been performed on Ti-24Nb (at.%) in two different microstructural conditions. Markedly different transformation behaviour was observed between these two conditions, including fully reversible superelastic behaviour below the apparent martensitic start temperature. These results could not be rationalised using thermally based transformation descriptions. As such, a new approach is introduced based upon the total stress level in a material.

Investigation on microstructure and martensitic transformation of neodymium-added NiTi shape memory alloys

2016 ◽  
Vol 30 (28) ◽  
pp. 1650286
Author(s):  
Dovchinvanchig Maashaa ◽  
Ulzii-Orshikh Dorj ◽  
Malrey Lee ◽  
Min Hi Lee ◽  
Chunwang Zhao ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
X Ray Diffraction ◽  
Martensitic Transformation Temperature ◽  
Scanning Calorimetry ◽  
Nd Addition ◽  
One Step ◽  
Niti Shape Memory Alloys ◽  
Niti Matrix ◽  
Electronic Microscope

The effect of rare earth element neodymium (Nd) addition on the microstructure and martensitic transformation behavior of Ni[Formula: see text]Ti[Formula: see text]Nd[Formula: see text] ([Formula: see text] = 0, 0.1, 0.3, 0.5 and 0.7 at.%) shape memory alloy was investigated by scanning electronic microscope, X-ray diffraction and differential scanning calorimetry. The results show that the microstructure of Ni–Ti–Nd ternary alloy consists of NiNd phase, NiTi2 and the NiTi matrix. A one-step martensitic transformation is observed in the alloys. The martensitic transformation temperature Ms increases sharply increasing 0.1–0.7 at.% Nd content is added.

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