Joule heating as a primary heating source mechanism was probed during spark plasma sintering (SPS) of pure metal powders (Fe, Ni and Cu). Resistance to electric path was estimated from voltage-current measurements obtained online during these experiments. Resistance was observed to saturate at the same value irrespective of the type of metal powder, after attaining a sintering temperature of ∼0.3Tm. This saturation in resistance is attributed primarily to the Joule heating that occurs at the graphite-foil and punch in an SPS system. © 2014 Acta Materialia Inc. All rights reserved.

Budaraju Srinivasa Murty

Department of Metallurgical and Materials Engineering

Ravi Sankar Kottada

Linford D. Pinto

electric conductivity

Joule heating

Spark plasma sintering

Densification

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

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Scripta Materialia

In the present investigation, nanocrystalline W and W-xRe (x = 3, 5 wt.%) alloy powders were produced by mechanical milling/alloying using high energy ball milling. The nanocrystalline nature (∼50 nm) of these powders was validated by the Rietveld refinement of their respective X-Ray diffraction patterns. Subsequently, spark plasma sintering of the ball milled powders was carried out. It was observed that pure W was not able to densify completely (relative density of 93%) at a temperature of 1500 °C. However, the addition of 5 wt.% Re resulted in near complete densification (relative density of 97%) at the same sintering temperature. The enhanced densification of W-Re powders is mainly attributed to the ductilising effect of Re assisted by the nanocrystallinity of powders, and the application of pressure during sintering. © 2019 The Society of Powder Technology Japan

Fulltext

Advanced Powder Technology

Effect of Re on microstructural evolution and densification kinetics during spark plasma sintering of nanocrystalline W

The present work reports the role of different atomic mobility induced localized pore evolution on densification during spark plasma sintering of nanocrystalline W-Mo alloy powder. The shrinkage (or expansion) behavior of cold compacted milled powders was studied using dilatometry during non-isothermal sintering up to 1600 °C. Subsequently, the milled powders were densified to ~95% relative density using spark plasma sintering up to 1600 °C. The enhanced localized Joule heating due to dynamically evolved porous structure could be attributed for the densification during spark plasma sintering. © 2018 Elsevier Ltd

Localized pore evolution assisted densification during spark plasma sintering of nanocrystalline W-5wt.%Mo alloy

In this paper, the theoretical framework of viscous flow deformation is presented as a model to investigate the inherent role of applied pressure in the densification of Fe-based amorphous alloy powder during spark plasma sintering. The proposed model revealed that the evolution of the structural geometry of the powder compact resulted in an amplification of the applied pressure to a larger contact pressure. The resulting pressure controlled compressive viscous flow deformation of the particles exhibited the contribution of increased applied pressure towards enhancement of densification and thus confirmed the validity of the present model for analyzing pressure-assisted sintering of amorphous alloy powder. The application of this theoretical model correctly predicted the trend of increasing final density of the compacts with pressure while further improvement on its accuracy can be attained upon establishment of the relative contribution of mass flow and deformation of powder particles towards their consolidation. © 2017

Journal of Alloys and Compounds

Pressure controlled micro-viscous deformation assisted spark plasma sintering of Fe-based bulk amorphous alloy

The densification kinetics during spark plasma sintering (SPS) of FeAl and NiAl powders were analyzed using a model proposed by Bernard-Granger and Guizard [10]. Creep parameters obtained through densification data are in good agreement with those obtained from conventional creep experiments. Validity of the model was illustrated for aluminides in the form of deformation mechanism maps. This validation assures plausible confidence to predict creep behavior using densification data obtained during pressure assisted sintering of metallic alloys. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Journal	Data powered by TypesetScripta Materialia
Publisher	Data powered by TypesetElsevier Ltd
ISSN	13596462
Open Access	No