DSC and Mössbauer Studies of Fe80B20 Crystallization

1993 ◽  
Vol 321 ◽  
Author(s):  
Federica Malizia ◽  
Franco Ronconi
Keyword(s):  
Differential Scanning Calorimetry ◽  
Growth Process ◽  
Isothermal Annealing ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Avrami Equation ◽  
Thermal Treatments ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
Crystalline Component

ABSTRACTDifferential Scanning Calorimetry has been used to investigate the mechanism of the isothermal crystallization kinetics in Fe80B20 Metallic glass. It is shown that the whole crystallization analysis must include, not only a crystal nucleation-and-growth process, but also a grain-growth process and that these two processes are separated in time during isothermal annealing. These processes have been studied directly finding the parameters which characterize their Mechanism. From the theoretical Johnson-Mehl-Avrami equation describing the nucleation-and-growth process, it was possible to calculate the evolution of the transformed fraction of the material as a function of the annealing time. To infer the meaning of the transformed fraction, samples subjected to different thermal treatments have been studied by Mössbauer Spectroscopy. Our results reveal that the transformed fraction is the sum of the crystalline component formed by all atoms located in the lattice of the grains and the interfacial component composed of atoms in the interfacial regions between grains.

Polyethylene Glycol (PEG) - Polyvinyl Alcohol Graft Copolymer System of Non-Isothermal Crystallization Kinetics

2011 ◽  
Vol 332-334 ◽  
pp. 1485-1489
Author(s):  
Mei Zhang ◽  
Tian Yu Xu ◽  
Yong Jia Liu ◽  
Da Hui Sun
Keyword(s):  
Differential Scanning Calorimetry ◽  
Polyethylene Glycol ◽  
Crystallization Kinetics ◽  
Graft Copolymers ◽  
Avrami Equation ◽  
Temperature Peak ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
Peak Intensity ◽  
Lower Temperature

The confined of PEG in PVA-g-PEG graft copolymers was investigated by differential scanning calorimetry. The crystallization kinetics was discussed by several methods. The results showed that the lower temperature peak (Tp) shifted to the lower temperature and its peak intensity also decreased with increasing the cooling rates, t1/2 decreased and G increased. The Tp of graft copolymers were lower than pure PEG and t1/2 of which were higher than pure PEG. The graft ratio had litter influence on t1/2. The results also showed that both Jeziorny method and the new method combing the Avrami equation described this system very well.

scholarly journals Analysis of the Crystallization Kinetics and Thermal Stability of the Amorphous Mg72Zn24Ca4 Alloy

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3583
Author(s):  
Bartosz Opitek ◽  
Janusz Lelito ◽  
Michał Szucki ◽  
Grzegorz Piwowarski ◽  
Łukasz Gondek ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
Isothermal Annealing ◽  
Amorphous Structure ◽  
Avrami Equation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Human Body Temperature ◽  
End Times

The aim of this study was to analyze the crystallization of the Mg72Zn24Ca4 metallic glass alloy. The crystallization process of metallic glass Mg72Zn24Ca4 was investigated by means of the differential scanning calorimetry. The glass-forming ability and crystallization are both strongly dependent on the heating rate. The crystallization kinetics, during the isothermal annealing, were modelled by the Johnson–Mehl–Avrami equation. Avrami exponents were from 2.7 to 3.51, which indicates diffusion-controlled grain growth. Local exponents of the Johnson–Mehl–Avrami equation were also calculated. In addition, the Mg phase—being the isothermal crystallization product—was found, and the diagram of the time–temperature phase transformation was developed. This diagram enables the reading of the start and end times of the crystallization process, occurring in amorphous ribbons of the Mg72Zn24Ca4 alloy on the isothermal annealing temperature. The research showed high stability of the amorphous structure of Mg72Zn24Ca4 alloy at human body temperature.

Reactions in Metal-Metalloid Multilayers

1993 ◽  
Vol 311 ◽  
Author(s):  
Robert Sinclair ◽  
Toyohiko J. Konno
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Reactive Systems ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Scanning Calorimetry ◽  
Compound Formation ◽  
Transmission Electron

ABSTRACTWe have studied the reactions at metal-metalloid interfaces using high resolution transmission electron microscopy, including in situ observation, and differential scanning calorimetry. There is contrasting behavior depending on the affinity for interaction or segregation. For reactive systems, compound formation ultimately results, but this can be preceded by solidstate amorphization. For non-reactive systems, crystallization of the metalloid is often achieved with nucleation and growth mediated by the metal phase.

The thermal fission-induced crystalline-to-amorphous transformation in U6Fe

1988 ◽  
Vol 3 (3) ◽  
pp. 453-460 ◽  
Author(s):  
Don M. Parkin ◽  
Reed O. Elliott
Keyword(s):  
Differential Scanning Calorimetry ◽  
Crystallization Behavior ◽  
Amorphous Material ◽  
Nucleation And Growth ◽  
Local Defect ◽  
Scanning Calorimetry ◽  
Dose Dependent ◽  
Limited Process ◽  
Total Resistivity ◽  
Crystalline Matrix

The crystalline-to-amorphous transformation in U6Fe produced by thermal fission fragment damage was studied using resistivity and differential scanning calorimetry. The results are described in terms of a model of radiation-produced defect buildup in the crystalline matrix followed by transformation of small regions to an amorphous phase when a critical local defect concentration is reached. This can occur directly in a single cascade or from cascade overlap. The total resistivity is modeled assuming an inhomogeneous media consisting of a crystalline matrix containing a dose-dependent concentration of defects and amorphous zones. The crystallization behavior is initially, starting at Tc = 388 K, a kinetically limited process of shrinkage of amorphous zones that gradually transforms to nucleation and growth in fully amorphous material at Tc = 555 K.

Diffusion-Controlled Nanocrystallization of the Fe73.5Cu1Nb3Si15.5B7 Finemet Amorphous Alloy

2008 ◽  
Vol 570 ◽  
pp. 120-125
Author(s):  
R.M. Ribeiro ◽  
R.S. de Biasi ◽  
D.R. dos Santos ◽  
Dílson S. dos Santos
Keyword(s):  
Differential Scanning Calorimetry ◽  
Amorphous Alloy ◽  
Small Angle ◽  
Nucleation And Growth ◽  
Amorphous Metallic Alloy ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
Diffusion Controlled

Crystallization of the amorphous metallic alloy Fe73.5 Cu1Nb3 Si8.5 B14 was investigated by ferromagnetic resonance (FMR), small angle in situ X-ray scattering (SAXS/WAXS) and differential scanning calorimetry (DSC). Only one crystalline phase was observed by WAXS and only one peak was observed by DSC. The activation energies, calculated from FMR and DSC data, were 287 kJ.mol-1 and 313.4 kJ.mol-1, respectively. The values calculated for the Avrami exponent were 0.98 (FMR) and 1.4 (DSC). These values correspond to different mechanisms of nucleation and growth; however, the SAXS /WAXS results suggest that the dominant mechanisms are nucleation and growth of crystals from small dimensions.

Non-Isothermal Crystallization Behavior of Poly(trimethylene Terephthalate-Co-Isophthalate) Copolyesters

2012 ◽  
Vol 535-537 ◽  
pp. 1413-1416
Author(s):  
Tien Wei Shyr ◽  
Chia Hsin Tung ◽  
Yan Ting Liu
Keyword(s):  
Isothermal Crystallization ◽  
Reaction Rate ◽  
Glassy State ◽  
Exothermic Peak ◽  
Avrami Equation ◽  
Scanning Calorimetry ◽  
Isothermal Crystallization Kinetics ◽  
1H Nuclear Magnetic Resonance ◽  
Thermal Nucleation ◽  
Trimethylene Terephthalate

Poly(trimethylene terephthalate-co-isophthalate) (TI) copolyesters were synthesized using different ratios of isophthalic acid (IPA) and Terephthalic acid (TPA) with 1,3-propanediol (1,3-PDO). The compositions of TI copolyesters were analyzed using 1H nuclear magnetic resonance (NMR). Non-isothermal melt- and cold-crystallization and subsequent melting behaviors were investigated using differential scanning calorimetry (DSC). For TI0, TI10, and TI20, non-isothermal crystallization kinetics were analyzed using a modified Avrami equation. The results show that the reaction rate of TPA with 1,3-PDO was similar with that of IPA with 1,3-PDO in TI copolyesters. Crystallization exothermic peak and melting endothermic peak were not observed in DSC traces with an increase of the relative amount of PIP to 41%. The Avrami exponent n is in the range of 3.5-4.2 for melt-crystallized TI copolyesters and between 3.0-3.2 for cold-crystallized copolyesters. It suggests that the crystallization from melt state corresponds to thermal nucleation but the crystallization from glassy state originates from predeterminated nuclei.

scholarly journals Analysis of Nucleation and Glass Formation by Chip Calorimetry

2021 ◽  
Vol 11 (16) ◽  
pp. 7652
Author(s):  
Meng Gao ◽  
Chengrong Cao ◽  
John H. Perepezko
Keyword(s):  
Differential Scanning Calorimetry ◽  
Crystal Nucleation ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Heating And Cooling ◽  
Chip Calorimetry ◽  
In Situ Formation ◽  
Materials Behavior

The advent of chip calorimetry has enabled an unprecedented extension of the capability of differential scanning calorimetry to explore new domains of materials behavior. In this paper, we highlight some of our recent work: the application of heating and cooling rates above 104 K/s allows for the clear determination of the glass transition temperature, Tg, in systems where Tg and the onset temperature for crystallization, Tx, overlap; the evaluation of the delay time for crystal nucleation; the discovery of new polyamorphous materials; and the in-situ formation of glass in liquid crystals. From these application examples, it is evident that chip calorimetry has the potential to reveal new reaction and transformation behavior and to develop a new understanding.

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