Smaller crystallites in sintered materials? A discussion of the possible mechanisms of crystallite size refinement during pulsed electric current-assisted sintering

Dudina, Dina V.; Анисимов, А. Н.; Mali, V. I.; Булина, Н. В.; Bokhonov, Boris B.

doi:10.1016/j.matlet.2015.01.042

Cited by 24 publications

(4 citation statements)

References 21 publications

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“…Zapata-Solvas et al 5 observed the enrichment of the grain boundaries of ZrB 2 sintered in the presence of graphite foil. Microstructural indications of the processes of chemical reduction of oxide lms on the metallic particles in certain regions of the Spark Plasma Sintered compact were found in our recent study: 6 very ne crystallites of copper were observed on the surface of ligaments of the sintered porous copper in the areas of the compact that had been in contact with the graphite foil during consolidation.…”

Section: Introductionmentioning

confidence: 75%

Carbon uptake during Spark Plasma Sintering: investigation through the analysis of the carbide “footprint” in a Ni–W alloy

et al. 2015

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Section: Introductionmentioning

confidence: 75%

Carbon uptake during Spark Plasma Sintering: investigation through the analysis of the carbide “footprint” in a Ni–W alloy

et al. 2015

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“…The large grain size after the SPS process can be explained via increasing mass transfer between grains under high temperature and pressure. In other words, the movement of grain boundary causes the smaller grains to merge inside the larger ones, leading to substantial growth [ 49 ]. As-made Cu 2 Se, in Figure 4 d,e, possesses larger particles compared to Cu 1.8 Se, which in turn grows to larger grains upon SPS.…”

Section: Resultsmentioning

confidence: 99%

Composition Tuning of Nanostructured Binary Copper Selenides through Rapid Chemical Synthesis and Their Thermoelectric Property Evaluation

et al. 2020

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Reduced energy consumption and environmentally friendly, abundant constituents are gaining more attention for the synthesis of energy materials. A rapid, highly scalable, and process-temperature-sensitive solution synthesis route is demonstrated for the fabrication of thermoelectric (TE) Cu2−xSe. The process relies on readily available precursors and microwave-assisted thermolysis, which is sensitive to reaction conditions; yielding Cu1.8Se at 200 °C and Cu2Se at 250 °C within 6–8 min reaction time. Transmission electron microscopy (TEM) revealed crystalline nature of as-made particles with irregular truncated morphology, which exhibit a high phase purity as identified by X-ray powder diffraction (XRPD) analysis. Temperature-dependent transport properties were characterized via electrical conductivity, Seebeck coefficient, and thermal diffusivity measurements. Subsequent to spark plasma sintering, pure Cu1.8Se exhibited highly compacted and oriented grains that were similar in size in comparison to Cu2Se, which led to its high electrical and low thermal conductivity, reaching a very high power-factor (24 µW/K−2cm−1). Density-of-states (DOS) calculations confirm the observed trends in electronic properties of the material, where Cu-deficient phase exhibits metallic character. The TE figure of merit (ZT) was estimated for the materials, demonstrating an unprecedentedly high ZT at 875 K of 2.1 for Cu1.8Se sample, followed by 1.9 for Cu2Se. Synthetic and processing methods presented in this work enable large-scale production of TE materials and components for niche applications.

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“…Aman et al [26] reported evidence of the unconventional neck formation in copper compacts sintered by pressureless SPS and suggested that the ejection mechanism was operating. In a study by Dudina et al [20], evidence of melting was found not only in the inter-particle regions when an electrolytic copper powder was processed by pressureless SPS (using an assembly shown in Figure 2b); some ligaments of the porous material had a re-solidified structure. When pressureless SPS experiments for conductive materials are designed in such a way that the sample can carry an electric current but was not pre-pressed before the sintering start, the distribution of electric current across the sample’s cross-section may be rather non-uniform, causing local melting effects (not confined to the inter-particle contacts).…”

Section: Fabrication Of Porous Materials By Partial Densification mentioning

confidence: 99%

“…The geometry of the assembly is, therefore, modified, such that the pressure is sustained by the die and not the sample. For that, short punches (Figure 2b) [20,21,22] or T-shape punches (Figure 2c) [23,24] can be used. In the case of short punches, the sum of the height of two punches and that of the sample is smaller than the height of the die.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Porous Materials by Spark Plasma Sintering: A Review

2019

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Spark plasma sintering (SPS), a sintering method that uses the action of pulsed direct current and pressure, has received a lot of attention due to its capability of exerting control over the microstructure of the sintered material and flexibility in terms of the heating rate and heating mode. Historically, SPS was developed in search of ways to preserve a fine-grained structure of the sintered material while eliminating porosity and reaching a high relative density. These goals have, therefore, been pursued in the majority of studies on the behavior of materials during SPS. Recently, the potential of SPS for the fabrication of porous materials has been recognized. This article is the first review to focus on the achievements in this area. The major approaches to the formation of porous materials by SPS are described: partial densification of powders (under low pressures, in pressureless sintering processes or at low temperatures), sintering of hollow particles/spheres, sintering of porous particles, and sintering with removable space holders or pore formers. In the case of conductive materials processed by SPS using the first approach, the formation of inter-particle contacts may be associated with local melting and non-conventional mechanisms of mass transfer. Studies of the morphology and microstructure of the inter-particle contacts as well as modeling of the processes occurring at the inter-particle contacts help gain insights into the physics of the initial stage of SPS. For pre-consolidated specimens, an SPS device can be used as a furnace to heat the materials at a high rate, which can also be beneficial for controlling the formation of porous structures. In sintering with space holders, SPS processing allows controlling the structure of the pore walls. In this article, using the literature data and our own research results, we have discussed the formation and structure of porous metals, intermetallics, ceramics, and carbon materials obtained by SPS.

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Smaller crystallites in sintered materials? A discussion of the possible mechanisms of crystallite size refinement during pulsed electric current-assisted sintering

Cited by 24 publications

References 21 publications

Carbon uptake during Spark Plasma Sintering: investigation through the analysis of the carbide “footprint” in a Ni–W alloy

Carbon uptake during Spark Plasma Sintering: investigation through the analysis of the carbide “footprint” in a Ni–W alloy

Composition Tuning of Nanostructured Binary Copper Selenides through Rapid Chemical Synthesis and Their Thermoelectric Property Evaluation

Fabrication of Porous Materials by Spark Plasma Sintering: A Review

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