Densification and Crystallization in Fe–Based Bulk Amorphous Alloy Spark Plasma Sintered in the Supercooled Liquid Region

Paul, Tanaji; Singh, Ashish Kumar; Harimkar, Sandip P.

doi:10.1002/adem.201700224

Cited by 14 publications

(7 citation statements)

References 45 publications

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“…The temperature in the center of a Fe-based alloy sample processed by SPS is about 50 degrees higher than the temperature of the wall of the graphite die, as calculated by Paul et al [27] for a graphite die of 20 mm inner diameter and 50 mm outer diameter. Therefore, in our work, consolidation of composites at 500 ºC as measured by the thermocouple inserted in a hole in the die wall can be considered as occurring within the supercooled liquid region of the glass.…”

Section: Characteristics Of the Fe66cr10nb5b19 Alloy Powder And Its Sps Behaviormentioning

confidence: 63%

Interaction between Fe66Cr10Nb5B19 metallic glass and aluminum during spark plasma sintering

Dudina

Bokhonov

Batraev

et al. 2021

Materials Science and Engineering: A

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In the area of metal matrix composites, novel reinforcing options are currently being evaluated. Particles of amorphous alloys present an interesting possibility to reinforce soft metals. In the present work, the interaction between Fe66Cr10Nb5B19 metallic glass and aluminum during Spark Plasma Sintering (SPS) was studied for the first time. In order to trace the phase and microstructural changes upon sintering, mixtures containing 20 vol.% and 50 vol.% of metallic glass were subjected to SPS at 500-570 ºC. After SPS at 500 ºC, no reaction layer between the metallic glass particles and aluminum was observed. After SPS at 570 ºC, a reaction layer containing Fe2Al5 and FeAl3 formed around the Fe-based cores. The Vickers hardness of composites obtained from mixtures containing 20 vol. % Fe66Cr10Nb5B19 at 540 ºC was 75 HV and increased to 280 HV after sintering at 570 ºC due to the formation of thicker reaction layers at the interface.The hardness of the composite sintered from the mixture containing 20 vol. % Fe66Cr10Nb5B19 at 570 ºC was between the values predicted by Reuss and Voigt models.Comparison of results of SPS of the powder mixtures with those of SPS of a precompacted pellet and electric current-free annealing suggests that local heating at the interface caused by interfacial resistance may be an important factor influencing the reaction advancement at the interface and the formation of Al-containing intermetallics.

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Section: Characteristics Of the Fe66cr10nb5b19 Alloy Powder And Its Sps Behaviormentioning

confidence: 63%

Interaction between Fe66Cr10Nb5B19 metallic glass and aluminum during spark plasma sintering

Dudina

Bokhonov

Batraev

et al. 2021

Materials Science and Engineering: A

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“…The metallic glass powder of composition Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6 (at.%) consisted of mostly spherical particles, with a mean size of about 40 μm 26,33 . A graphite die was lined with a graphite foil along its internal wall of diameter 20 mm to facilitate movement of graphite punches within.…”

Section: Discussionmentioning

confidence: 99%

“…For the cost effective application of iron based metallic glasses with high strength as structural components, it is necessary to circumvent the problem of processing these materials into bulk shapes. One of the promising methods is the application of powder consolidation techniques such as hot pressing 23 , warm extrusion 24 , hot isostatic pressing 25 and spark plasma sintering (SPS) 26 . SPS is particularly advantageous as it enables the sintering of dense compacts at lower temperatures and shorter cycles [27][28][29][30] primarily due to Joule heating resulting from the passage of current through the powder compact 31,32 .…”

mentioning

confidence: 99%

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

Paul

Singh

Littrell

et al. 2020

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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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“…This was done to make up for the difference in the samples' real temperature caused by the mode of heating. The temperature of the conductive specimens is always higher than the temperature of the die wall; in the case of relatively low sintering temperatures, the difference is several tens of degrees [26]. In the SPS process, local overheating effects at the inter-particle contacts can play a significant role in densification.…”

Section: Structural Characteristics Of the Sintered Compositesmentioning

confidence: 99%

The Benefit of the Glassy State of Reinforcing Particles for the Densification of Aluminum Matrix Composites

et al. 2022

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In metallic glass-reinforced metal matrix composites, the glassy phase can serve a dual purpose: (i) it can behave as soft binder and porosity remover during consolidation; and (ii) it can act as the hard reinforcing phase after densification. The present work aimed to demonstrate the benefit of the glassy reinforcing particles for the densification of aluminum matrix composites. The consolidation behavior of Al–50 vol.% Fe-based alloy mixtures prepared using a glassy Fe66Cr10Nb5B19 alloy powder (Tg = 521 °C, Tx = 573 °C) or a crystalline Fe62Cr10Nb12B16 alloy powder was studied under spark plasma sintering (SPS) and hot pressing (HP) conditions. The powders were consolidated by heating above the glass transition temperature of the glassy alloy (up to 540 °C in SPS and 570 °C in HP). When the coarse aluminum powder was used, the reinforcing particles formed chains within the microstructure. In composites formed from the fine Al powder, the particles of the Fe-based alloy were separated from each other by the metallic matrix, and the tendency to form agglomerates was reduced. The glassy state of the alloy was shown to be beneficial for densification, as the metallic glass acted as a soft binder. The densification enhancement effect was more pronounced in the case of reinforcing particles forming chains. The hardness of the Al–50 vol.% glassy Fe66Cr10Nb5B19 composites obtained by SPS was twice the hardness of the unreinforced sintered aluminum (110 HV1 versus 45 HV1).

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Densification and Crystallization in Fe–Based Bulk Amorphous Alloy Spark Plasma Sintered in the Supercooled Liquid Region

Cited by 14 publications

References 45 publications

Interaction between Fe66Cr10Nb5B19 metallic glass and aluminum during spark plasma sintering

Interaction between Fe66Cr10Nb5B19 metallic glass and aluminum during spark plasma sintering

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

The Benefit of the Glassy State of Reinforcing Particles for the Densification of Aluminum Matrix Composites

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