Crystallization of Amorphous Ribbon in NiTi-Cu Shape Memory Alloy

1997 ◽  
Vol 481 ◽  
Author(s):  
F. Yang ◽  
J. L. Ma ◽  
Z. J. Pu ◽  
K. H. Wu
Keyword(s):  
Shape Memory ◽  
Crystallization Kinetics ◽  
System Analysis ◽  
Crystallization Process ◽  
Amorphous Material ◽  
Amorphous Ribbon ◽  
Continuous Heating ◽  
Isothermal Model ◽  
Heating Mode ◽  
Kinetics Of

ABSTRACTThe objective of this work is to study the crystallization process of the amorphous ribbon of NiTi-Cu based shape memory alloys. An amorphous material with a composition of Ti50Ni25Cu25 was used to conduct this study. First, a study was conducted to understand the crystallization kinetics of this amorphous material at the isothermal model and continuous heating mode, respectively. The characteristic parameters associated with the crystallization process, such as the start and finish time for isothermal crystallization, the peak temperature for continuous heating crystallization, and activation energy, are obtained. Based on the study of experimental data of crystallization kinetics, a series of isothermal annealing experiments was conducted to study the crystallization process and microstructure of fully crystallized materials. The TEM micrograph shows the crystal phase growths in the amorphous matrix as a perfect geometric sphere. A system analysis was conducted to explain the crystallization micro-mechanism.

Fabrication of Fine Grain Size Shape Memory Alloys Through Crystallization of Amorphous Ribbon

1995 ◽  
Vol 400 ◽  
Author(s):  
J. D. Shi ◽  
J. L. Ma ◽  
Y. Gao ◽  
Z. J. Pu ◽  
K. H. Wu
Keyword(s):  
Grain Size ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Amorphous Materials ◽  
Crystallization Process ◽  
Amorphous Material ◽  
Continuous Heating ◽  
Fine Grain ◽  
Mean Grain Size ◽  
The Mean

AbstractThe objective of this work is to fabricate fine grain size NiTi-based shape memory alloys through crystallization of amorphous materials. An amorphous material with a composition of Ti50Ni25Cu25 was used as a sample for this study. First, a systematic investigation was conducted to understand the kinetics of the crystallization process of amorphous materials under an isothermal mode and under a continuous heating mode, respectively. The characteristic parameters associated with the crystallization process, such as the starting and finishing times for the isothermal crystallization process, the peak temperature for the continuous heating crystallization process, and the activation energy of the material were determined. Based on the results of the kinetic study, a series of isothermal annealing experiments were conducted to characterize the microstructure of the fully crystallized materials. The TEM micrographs indicate that the mean grain size of the fully crystallized Ti50Ni25Cu25 alloy is independ of isothermal temperature. The mean grain size is around 400-500nm, which is 1/10 of the grain size of usual NiTi based shape memory alloys. In addition, the crystallization micro-mechanism of the amorphous material is discussed based on TEM observations.

scholarly journals Influence of Annealing Temperature on the Crystallization Kinetics of Fe82Si8B10 Amorphous Ribbon

2020 ◽  
Vol 11 (1) ◽  
pp. 107-112
Author(s):  
A Said Sikder ◽  
SD Nath ◽  
SS Sikder
Keyword(s):  
Crystallization Kinetics ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Amorphous Ribbon ◽  
Primary Crystallization ◽  
Soft Magnetic Materials ◽  
Power Transformers ◽  
Soft Magnetic ◽  
Potential Applications ◽  
Kinetics Of

Amorphous soft magnetic materials have significant potential applications in specialist power transformers and in inductive devices. With the composition of Fe82Si8B10, 82% of the transition metals Fe and about 18% of metalloid or glass-former elements like B and Si are strongly magnetic at room temperature and offer dynamic opportunities for engineering applications. The crystallization kinetics has been studied by differential thermal analysis (DTA). The sample was annealed in a controlled way in the temperature range of 350-450°C at constant annealing time one hour. The kinetics of primary crystallization α-Fe(Si) phase and secondary crystallization Fe2B phase was studied as affected due to temperature. The sample annealed at 350oC temperature is almost unchanged which is still lower than that of primary crystallization temperature but the same condition when sample annealed at 450°C completely shows that the primary crystallization α-Fe(Si) phase has vanished and crystallization event took place to a good extent. Journal of Engineering Science 11(1), 2020, 107-112

The Crystallization Kinetics of Ni-Mn-Ga Magnetic Shape Memory Alloy Thin Films

2019 ◽  
Vol 48 (4) ◽  
pp. 2137-2143
Author(s):  
Jiachen Zhu ◽  
Changlong Tan ◽  
WenBin Zhao ◽  
ZhaiPing Yang ◽  
Kun Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Crystallization Kinetics ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloy ◽  
Kinetics Of

Glass Forming Ability and Crystallization Kinetics of Al-Mg-Ni-La Metallic Glasses

2014 ◽  
Vol 960-961 ◽  
pp. 161-164 ◽  
Author(s):  
Juan Mu ◽  
Hai Feng Zhang
Keyword(s):  
Crystallization Kinetics ◽  
Glass Forming Ability ◽  
Continuous Heating ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Glass Forming ◽  
Dsc Measurements ◽  
Mg Addition ◽  
Kinetics Of ◽  
Thermal Stability Of

Glass forming ability and crystallization kinetics of Al-Mg-Ni-La alloys have been investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The maximum thickness achievable in glasses of Al76Mg11Ni8La5and Al69Mg18Ni8La5ribbons were 200 and 120 μm, respectively. The crystallization temperature and peak temperature indicated by DSC measurements displayed dependence on the heating rate during continuous heating, and were coincident with Lanoka’s relationship. The activation energies for the crystallization reactionExwere obtained from the Kissinger’s equation. The results show the Mg addition is beneficial to the thermal stability of the amorphous phase.

Crystallization Kinetics in Cu64.5Zr35.5 Binary Metallic Glass

2017 ◽  
Vol 727 ◽  
pp. 233-238 ◽  
Author(s):  
Qian Gao ◽  
Zeng Yun Jian ◽  
Jun Feng Xu ◽  
Man Zhu
Keyword(s):  
Activation Energy ◽  
Grain Growth ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
Crystallization Kinetic ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Growth Activation ◽  
Local Activation Energy ◽  
Kinetics Of

The crystallization kinetics of melt-spun Cu64.5Zr35.5 amorphous alloy ribbons was investigated using differential scanning calorimetry (DSC) at different heating rates. Besides, the Kissinger and isoconversional approaches were used to obtain the crystallization kinetic parameters. As shown in the results, the activation energies for glass transition and crystallization process at the onset, peak and end crystallization temperatures were obtained by means of Kissinger equation to be 577.65 ± 34, 539.86 ± 54, 518.25 ± 20 and 224.84 ± 2 kJ/mol, respectively. The nucleation activation energy Enucleation is greater than grain growth activation energy Egrowth, indicating that the nucleation process is harder than grain growth. The local activation energy Eα decreases in the whole crystallization process, which suggests that crystallization process is increasingly easy.

Crystallization Kinetics of the Cu47.5Zr47.5Al5 Bulk Metallic Glass under Continuous and Iso-Thermal Heating

2011 ◽  
Vol 99-100 ◽  
pp. 1052-1058 ◽  
Author(s):  
Chun Xia Hu ◽  
Gai Lian Li ◽  
Yang Shi
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
The Body ◽  
Avrami Exponent ◽  
Isothermal Kinetics ◽  
Continuous Heating ◽  
Local Activation ◽  
Body Center Cubic ◽  
Local Activation Energy ◽  
Kinetics Of

The crystallization kinetics of Cu47.5Zr47.5Al5 BMG was studied by differential scanning calorimetry (DSC) using the mode of continuous heating and isothermal annealing. It is found that Tg, Tx, and Tp, display a dependence on the heating rate in the case of continuous heating. The activation energies, Eg, Ex and Tp determined by the Kissinger method, yield 445, 264 and 285 kJ/mol, respectively. The local activation energy, E(x), was determined by the Doyle-Ozawa method, which gives the average activation energy 204 kJ/mol. On the other hand, the isothermal kinetics was modeled by the Johnson-Mehl-Avrami (JMA) equation, the Avrami exponent versus crystallization fraction was calculated at different temperatures. Details of nucleation and growth behaviors are discussed in terms of the local Avrami exponent and local activation energy during the isothermal crystallization. X-ray shows that the quenched BMG only includes the glass single phase. The BMG heated to 873 K has the precipitation of the body-center cubic (BCC) CuZr.

Effect of high pressure on relaxation dynamics and crystallization kinetics of chiral liquid crystal in its smectic phase

2021 ◽  
Author(s):  
Anna Drzewicz ◽  
Małgorzata Jasiurkowska-Delaporte ◽  
Ewa Juszyńska-Gałązka ◽  
Mirosław Gałązka ◽  
Wojciech Zając ◽  
...  
Keyword(s):  
High Pressure ◽  
Liquid Crystal ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
Smectic Phase ◽  
Relaxation Dynamics ◽  
Chiral Liquid Crystal ◽  
The Impact ◽  
Kinetics Of

The impact of high pressure on relaxation dynamics and the crystallization process in the smectic phase with antiferroelectric properties ( phase) of novel liquid crystal was studied.

scholarly journals Crystallization kinetics of K2O·TiO2·3GeO2 glass studied by DTA

2008 ◽  
Vol 40 (3) ◽  
pp. 333-338 ◽  
Author(s):  
S. Grujic ◽  
N. Blagojevic ◽  
M. Tosic ◽  
V. Zivanovic ◽  
J. Nikolic
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Particle Size ◽  
Differential Thermal Analysis ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Samples ◽  
Kinetics Of

Crystallization kinetics of K2O?TiO2?3GeO2 glass was investigated by differential thermal analysis (DTA). Experiments were performed on powder samples with a particle size < 0.037 mm. The glass samples were heated at different rates in the temperature range 20-750?C. The kinetic parameters, activation energy for the crystallization process, Ec and Avrami exponent, n were calculated. Powder X-ray diffraction analysis (XRD) of crystallized glass reveals the presence of crystalline K2O?TiO2?3GeO2 indicating polymorphic crystallization with interface controlled crystal growth.

The structure of thin films sputter deposited from a Ba2 Si2TiO8 ceramic target

1988 ◽  
Vol 3 (1) ◽  
pp. 105-111 ◽  
Author(s):  
H. Yamauchi ◽  
R. J. White ◽  
M. Ayukawa ◽  
T. C. Murray ◽  
J. W. Robinson
Keyword(s):  
Thin Films ◽  
Crystallization Process ◽  
Amorphous Material ◽  
Appreciable Amount ◽  
X Ray Diffraction ◽  
Fixed Temperature ◽  
Ceramic Target ◽  
Sputter Deposited ◽  
Substrate Temperatures ◽  
Kinetics Of

Thin films were sputter deposited from a Fresnoite (Ba2Si2TiO8) ceramic target at substrate temperatures lower than 175°C. The as-deposited thin films were near amorphous with a void network morphology. In spite of the fact that the film compositions were shifted from stoichiometry, x-ray diffraction studies showed that the films crystallized to form randomly oriented Fresnoite grains. The crystallization kinetics were quite sluggish and the resultant activation energy for the crystallization process was 370 ± 30 kJ/mol. Even after annealing for 10 h at 750°C an appreciable amount of amorphous material remained in the thin films. The short-range order in this amorphous material was changed from that of the as-deposited thin films. The overall devitrification kinetics of amorphous Fresnoite thin films at a fixed temperature were represented theoretically by an equation of Tool's type.

Orthogonal Smectic Layers Favour Nucleation through Diffusioncontrolled Transformations: A Systematic Crystallization Kinetics Study

2002 ◽  
Vol 57 (5) ◽  
pp. 226-232 ◽  
Author(s):  
P. A. Kumar ◽  
Pisupati Swathi ◽  
V. G. K. M. Pisipati
Keyword(s):  
Differential Scanning Calorimetry ◽  
Crystal Growth ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
Avrami Exponent ◽  
Kinetics Study ◽  
Nucleation Process ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Kinetics Of

Systematic investigations of the crystallization kinetics of two representative compounds of p-phenylbenzylidene-p´ -alkylanilines are performed, using differential scanning calorimetry, to study the influence of the kinetophase (occurs prior to the crystal phase) on the nucleation process. The dimensionality of the crystal growth and the related crystallization process are discussed in terms of the Avrami parameters n and b. The trend in the magnitude of the Avrami exponent n supports the occurrence of temperature-dependent transformations in the orthorhombic molecular array.

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