Kinetics of isochronal crystallization in a Fe-based amorphous alloy

Paul, Tanaji; Loganathan, Archana; Agarwal, Arvind; Harimkar, Sandip P.

doi:10.1016/j.jallcom.2018.04.133

Cited by 41 publications

(14 citation statements)

References 58 publications

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“…However, there is no report that has extended this technique for non-polymeric systems such as amorphous alloys and silica glasses. Some researchers have attempted to quantify the crystallization process of Fe-based metallic glasses [45][46] using an isochronal DSC experiment. This approach was introduced by Johnson-Mehl-Avrami in order to study the kinetics of isothermal solidstate phase transformations (here glass to crystal) [47][48].…”

Section: Introductionmentioning

confidence: 99%

A method to quantify crystallinity in amorphous metal alloys: A differential scanning calorimetry study

et al. 2020

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We developed and describe a differential scanning calorimetry method for calculating the initial crystallinity, change of crystallinity and crystallinity percentage of amorphous metal alloys as a function of temperature. Using thermodynamic enthalpies of amorphous, crystalline and partially devitrified specimens, our methodology is capable of determining crystallinity percentages as low as a few percent. Moreover, the linear relationship between the set (pre-determined) and calculated crystallinities of experimental samples indicates that there is no need to prepare calibration samples before measuring the crystallinity percentage of target samples. This technique also eliminates the need for expensive in situ accessories, such as those required in electron microscopy. Thus, the technique is highly relevant as a primary technique for characterization of devitrification behavior in amorphous materials.

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Section: Introductionmentioning

confidence: 99%

A method to quantify crystallinity in amorphous metal alloys: A differential scanning calorimetry study

et al. 2020

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“…An equivalent, constant growth exponent n holds for every single transformation and is given according to the following equation [ 36 , 37 , 38 , 39 ] (irrespective of whether it proceeds according to continuous, site saturation or mixed nucleation mechanisms [ 18 ]):

Therefore, for a series of isochronal transformations, the value of a described by non-isokinetics changes with the heating rate.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

A Non-Isokinetic Approach for Modeling Solid-State Transformations: Application to Crystallization of a Fe-B Amorphous Alloy

Zhang

Liu

2021

Materials

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Solid-state phase transformations like crystallization of amorphous alloys can be described by an analytical model incorporating a nucleation index a. However, this model cannot be used to examine isochronal transformations with abrupt changing of enthalpy differences performed with differential scanning calorimetry. Based on the model, a non-isokinetic approach is proposed and applied to analyze the isochronal crystallization kinetics of Fe85B15 amorphous alloy. The approach enabled us to obtain the kinetic parameters and activation energies for nucleation and growth.

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“…In particular, a value of n less than 1.5, as in the present case, shows that the evolution of (Fe,Cr) 23 C 6 crystals within the iron based metallic glass during isothermal annealing both at 700 °C as well as 725 °C occurs by diffusional transformation from pre-existing nuclei 58,59 . This transformation occurs with the growth of these crystallites alongside a decreasing nucleation rate, thereby being a primarily growth controlled process 21 . It was observed from Fig.…”

Section: Isothermal Crystallization Kineticsmentioning

confidence: 99%

Crystallization Mechanism in Spark Plasma Sintered Bulk Metallic Glass Analyzed using Small Angle Neutron Scattering

Paul

Singh

Littrell

et al. 2020

Sci Rep

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Understanding the thermal stability of metallic glasses is critical to determining their safe temperatures of service. In this paper, the crystallization mechanism in spark plasma sintered Fe 48 cr 15 Mo 14 Y 2 c 15 B 6 metallic glass is established by analyzing the crystal size distribution using x-ray diffraction, transmission electron microscopy and in-situ small angle neutron scattering. Isothermal annealing at 700 °C and 725 °C for 100 min resulted in the formation of (Fe,Cr) 23 c 6 crystals, measured from transmission electron micrographs, to be from 10 to 30 nm. The small angle neutron scattering intensity measured in-situ, over a Q-range of 0.02 to 0.3 Å −1 , during isothermal annealing of the sintered samples, confirmed the presence of (Fe,Cr) 23 c 6 crystals. The measured scattering intensity, fitted by the maximum entropy model, over the Q-range of 0.02 to 0.06 Å −1 , revealed that the crystals had radii ranging from 3 to 18 nm. The total volume fraction of crystals were estimated to be 0.13 and 0.22 upon isothermal annealing at 700 °C and 725 °C for 100 min respectively. The mechanism of crystallization in this spark plasma sintered iron based metallic glass was established to be from pre-existing nuclei as confirmed by Avrami exponents of 0.25 ± 0.01 and 0.39 ± 0.01 at the aforesaid temperatures.

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Kinetics of isochronal crystallization in a Fe-based amorphous alloy

Cited by 41 publications

References 58 publications

A method to quantify crystallinity in amorphous metal alloys: A differential scanning calorimetry study

A method to quantify crystallinity in amorphous metal alloys: A differential scanning calorimetry study

A Non-Isokinetic Approach for Modeling Solid-State Transformations: Application to Crystallization of a Fe-B Amorphous Alloy

Crystallization Mechanism in Spark Plasma Sintered Bulk Metallic Glass Analyzed using Small Angle Neutron Scattering

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