Crystallization kinetics in Fe−B−Si metallic glasses

Ramanan, V. R. V.; Fish, G. E.

doi:10.1063/1.330797

Cited by 144 publications

(25 citation statements)

References 11 publications

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“…According to the ternary diagram of thermodynamic parameters and glass forming ability, presented by many authors [13,14] in this area, Fe 78 Si 9 B 13 lies in the hypoeutectic (Fe rich) region. Moreover, decrease of Fe content will rapidly increase the melts' excess heat capacity E P C , while decrease its forming entropy and forming Gibbs energy [14] .…”

Section: Resultsmentioning

confidence: 99%

Crystallization of Fe78Si9B13 bulk crystaline/amorphous (c/a) composite

Jin

Wang

Niu

et al. 2008

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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A metallic crystalline/amorphous (c/a) bulk composite was prepared by the slow cooling method after remelting the amorphous Fe 78 Si 9 B 13 ribbon. By X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscope (SEM), the composite consists of the primary dendrite α-Fe (without Si) as well as the amorphous matrix. After being anneal at 800 K, the uniform spheroid particles are formed in the c/a composite, which does not form in the amorphous ribbon under the various annealing process. Energy dispersive analysis of X-rays (EDAX), SEM and XRD were applied to give more detailed information. The formation and evolution of the particle may stimulate the possible application of the Fe-matrix amorphous alloy.

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Section: Resultsmentioning

confidence: 99%

Crystallization of Fe78Si9B13 bulk crystaline/amorphous (c/a) composite

Jin

Wang

Niu

et al. 2008

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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“…Dicha energía de activación resultó ser (440±29) kJ/mol. Este valor se encuentra en el rango reportado previamente [8,9].…”

Section: Resultados Y Discusiónunclassified

Microscopía fototérmica para el estudio de transformaciones de fase

2018

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RESUMENSe presenta el desarrollo de un novedoso sistema que permite el mapeo con alta resolución espacial de la difusividad térmica en función de la temperatura hasta 1800K. El sistema se basa en una técnica fototérmica recientemente desarrollada por el grupo, consistente en la medición con un láser de prueba de la curvatura inducida por el calentamiento con un láser modulado. La utilización de tecnología de fibras ópticas provee una alta robustez al equipo. Un horno para microscopio permite realizar rampas a velocidad controlada para el estudio de transiciones de fase y la medición de la difusividad térmica en función de la temperatura. Se pueden establecer mesetas para hacer barridos espaciales con resolución microscópica para el estudio de la evolución de las fases o hacer tratamientos térmicos in situ para estudiar luego la distribución espacial de las fases presentes. En este trabajo se presenta un ejemplo, donde la señal es colectada para un punto fijo y para una dada frecuencia de modulación, en función de la temperatura de la muestra. Se diseña para ello un sistema de corrección de enfoque que compensa la deriva térmica generada por la expansión térmica del sistema. El desplazamiento lateral es corregido utilizando un algoritmo de correlación y la imagen de la cámara. Este dispositivo fue utilizado para determinar la transición de fase de una muestra testigo. Estas capacidades se muestran a partir de la determinación de la energía de activación de la transformación de fase amorfo-cristal de una aleación de Fe-B-Si.Palabras clave: transformaciones de fase, técnica fototérmica, difusividad térmica, microscopía. ABSTRACTA novel system allowing a high spatial resolution mapping of the thermal diffusivity as a function of temperature up to 1800 K is presented. The system is based on a photothermal technique recently developed by the group, consisting in measuring, with a probe laser beam, the curvature induced by local heating with a modulated pump laser. A microscope heating stage was added to perform temperature ramp and soak that can be used for phase transition and thermal diffusivity determinations as functions of temperature. Spatial scans with microscopic resolution can be performed to study phases evolution at constant temperature for in situ thermal treatments and subsequent study of the spatial phase distribution. In this work an example is presented where the signal at a fixed point and constant modulation frequency is collected as a function of the temperature of the sample. A focus correction device was added to compensate for the thermal drift due to the thermal expansion of the system. The lateral displacement was corrected using a cross correlation algorithm and the camera image. This device was used to determine phase transition temperature of a test sample. These capabilities are shown with the determination of the activation energy for the phase transformation glasscrystal of a Fe-B-Si alloy.

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“…The study of amorphous iron-based alloys has been extensive by now, and the amorphous to crystalline transition in bulk samples has been fairly well understood [1][2][3][4][5]. Mechanical and magnetic properties of these alloys change by thermal and other treatments on the amorphous or on the crystalline states, where the chemical composition, sample homogeneity and concentration of nucleation sites and defects determine the final properties of the alloy [6].…”

Section: Introductionmentioning

confidence: 99%

Vickers Microhardness and Hyperfine Magnetic Field Variations of Heat Treated Amorphous Fe78Si9B13 Alloy Ribbons

et al. 2005

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Amorphous Fe 78 Si 9 B 13 alloy ribbons were heat treated between 296 and 763 K, using heating rates between 1 and 4.5 K/min. Whereas one ribbon partially crystallized at T x = 722 K, the other one partially crystallized at T x = 763 K. The partially crystallized ribbon at 722 K, heat treated using a triangular form for the heating and cooling rates, was substantially less fragile than the partially crystallized at 763 K where a tooth saw form for the heating and cooling rates was used. Vickers microhardness and hyperfine magnetic field values behaved almost concomitantly between 296 and 673 K. The Mössbauer spectral line widths of the heat-treated ribbons decreased continuously from 296 to 500 K, suggesting stress relief in this temperature range where the Vickers microhardness did not increase. At 523 K the line width decreased further but the microhardness increased substantially. After 523 K the line width behave in an oscillating form as well as the microhardness, indicating other structural changes in addition to the stress relief. Finally, positron lifetime data showed that both inner part and surface of Fe 78 Si 9 B 13 alloy ribbons were affected distinctly. Variations on the surface may be the cause of some of the high Vickers microhardness values measured in the amorphous state.

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Crystallization kinetics in Fe−B−Si metallic glasses

Cited by 144 publications

References 11 publications

Crystallization of Fe78Si9B13 bulk crystaline/amorphous (c/a) composite

Crystallization of Fe78Si9B13 bulk crystaline/amorphous (c/a) composite

Microscopía fototérmica para el estudio de transformaciones de fase

Vickers Microhardness and Hyperfine Magnetic Field Variations of Heat Treated Amorphous Fe78Si9B13 Alloy Ribbons

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