scholarly journals Direct observation of the processes near particle-to-particle contacts at electric pulse consolidation of titanium powder

2019 ◽  
Vol 488 (5) ◽  
pp. 504-507
Author(s):  
A. S. Rogachev ◽  
S. G. Vadchenko ◽  
V. A. Kudryashov ◽  
A. S. Shchukin ◽  
M. I. Alymov
Keyword(s):  
High Speed ◽  
Pulse Heating ◽  
Electric Pulse ◽  
Liquid Phase Sintering ◽  
Powder Materials ◽  
Plasma Sintering ◽  
Electric Current Pulses ◽  
Spark Plasma ◽  
Powder Particles ◽  
Electric Pulse Heating

Direct high-speed micro-video records prove the existence of highly overheated zones at the contacts of powder particles during short (~ 1 ms) electric current pulses. The value of overheating can exceed 1600 degrees and lead to the formation of liquid-phase sintering necks, the dimensions of which are well correlated with the size of the overheated zones. The micro-uniformity of the temperature field in the electric pulse heating allow understanding the unusually high consolidation rates of powder materials observed in spark plasma sintering.

Spark plasma sintering of WC – 10 Co nanopowders with various carbon content obtained by plasma-chemical method

2020 ◽  
pp. 73-86
Author(s):  
Yu. V. Blagoveshchenskiy ◽  
◽  
N. V. Isaeva ◽  
E. A. Lantsev ◽  
M. S. Boldin ◽  
...  
Keyword(s):  
Activation Energy ◽  
Carbon Content ◽  
Spark Plasma Sintering ◽  
High Speed ◽  
Diffusion Creep ◽  
Powder Materials ◽  
Plasma Chemical ◽  
Colloidal Graphite ◽  
Plasma Sintering ◽  
Spark Plasma

The features of high-speed sintering of WC – Co nanopowders with various contents of excess carbon (colloidal graphite) were studied. To obtain powders, a process was used that included plasma-chemical and low-temperature syntheses and a chemical-metallurgical method of applying ultrathin cobalt layers by precipitation from a solution of salts. The consolidation of powder materials was carried out by the method of high-speed Spark Plasma Sintering. It was found that an increase in the concentration of free carbon (colloidal graphite) has the greatest effect on the shrinkage and sintering rate at the stage of intense shrinkage of WC-Co nanopowders. It is shown that an increase in the carbon content in the composition of nanopowders leads to a decrease in the value of sintering activation energy at the stage of intense shrinkage.It has been established that the process of nanopowder compaction at the intense shrinkage stage is determined by the intensity of the plastic flow and the grain boundary diffusion of cobalt. It is shown that the mechanism of plastic deformation of the γ-phase based on cobalt corresponds to the Coble diffusion creep. It was found that an increase in carbon content leads to decreased in activation energy at the intense shrinkage and does not significantly affect at stage III of sintering where decrease in the shrinkage intensity is observed. It was shown that a decrease in the sintering activation energy is due to a decrease in the tungsten concentration in the γ-phase.

Effect of Spark Plasma Sintering on the Microstructure Evolution and Properties of M3:2 High-Speed Steel

2014 ◽  
Vol 788 ◽  
pp. 329-333
Author(s):  
Rui Zhou ◽  
Xiao Gang Diao ◽  
Jun Chen ◽  
Xiao Nan Du ◽  
Guo Ding Yuan ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Spark Plasma Sintering ◽  
High Speed ◽  
Bending Strength ◽  
Sintering Temperature ◽  
High Speed Steel ◽  
Continuous Heating ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Impact

Effects of sintering temperatures on the microstructure and mechanical performance of SPS M3:2 high speed steel prepared by spark plasma sintering was studied. High speed steel sintering curve of continuous heating from ambient temperature to 1200°C was estimated to analyze the sintering processes and sintering temperature range. The sintering temperature within this range was divided into groups to investigate hardness, relative density and microstructure of M3:2 high-speed steel. Strip and quadrate carbides were observed inside the equiaxed grains. SPS sintering temperature at 900°C can lead to nearly full densification with grain size smaller than 20μm. The hardness and bending strength are higher than that of the conventionally powder metallurgy fabricated ones sintered at 1270°C. However, fracture toughness of the high speed steel is lower than that of the conventional powder metallurgy steels. This can be attributed to the shape and distribution of M6C carbides which reduce the impact toughness of high speed steels.

scholarly journals Powder Metallurgy Processing and Mechanical Properties of Controlled Ti-24Nb-4Zr-8Sn Heterogeneous Microstructures

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1626
Author(s):  
Benoît Fer ◽  
David Tingaud ◽  
Azziz Hocini ◽  
Yulin Hao ◽  
Eric Leroy ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Ball Milling ◽  
Processing Route ◽  
Fine Grain ◽  
Plasma Sintering ◽  
3D Network ◽  
Spark Plasma ◽  
Powder Particles ◽  
Heterogeneous Microstructures

This paper gives some insights into the fabrication process of a heterogeneous structured β-metastable type Ti-24Nb-4Zr-8Sn alloy, and the associated mechanical properties optimization of this biocompatible and low elastic modulus material. The powder metallurgy processing route includes both low energy mechanical ball milling (BM) of spherical and pre-alloyed powder particles and their densification by Spark Plasma Sintering (SPS). It results in a heterogeneous microstructure which is composed of a homogeneous 3D network of β coarse grain regions called “core” and α/β dual phase ultra-fine grain regions called “shell.” However, it is possible to significantly modify the microstructural features of the alloy—including α phase and shell volume fractions—by playing with the main fabrication parameters. A focus on the role of the ball milling time is first presented and discussed. Then, the mechanical behavior via shear tests performed on selected microstructures is described and discussed in relation to the microstructure and the probable underlying deformation mechanism(s).

Spark plasma sintering for high-speed diffusion bonding of the ultrafine-grained near-α Ti–5Al–2V alloy with high strength and corrosion resistance for nuclear engineering

2019 ◽  
Vol 54 (24) ◽  
pp. 14926-14949 ◽  
Author(s):  
Vladimir Nikolaevich Chuvil’deev ◽  
Aleksey Vladimirovich Nokhrin ◽  
Vladimir Ilyich Kopylov ◽  
Maksim Sergeevich Boldin ◽  
Mikhail Mikhaylovich Vostokov ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Spark Plasma Sintering ◽  
Diffusion Bonding ◽  
High Speed ◽  
High Strength ◽  
Nuclear Engineering ◽  
Plasma Sintering ◽  
Ultrafine Grained ◽  
Spark Plasma

Synthesis of Bulk Quasicrystals by Spark Plasma Sintering

2000 ◽  
Vol 643 ◽  
Author(s):  
E. Fleury ◽  
J.H. Lee ◽  
S.H. Kim ◽  
G.S. Song ◽  
J.S. Kim ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Spark Plasma Sintering ◽  
Vickers Microhardness ◽  
Secondary Phases ◽  
Hot Press ◽  
Plasma Sintering ◽  
Short Period ◽  
Spark Plasma ◽  
Powder Particles ◽  
Sintering Method

AbstractSpark plasma sintering method was applied to Al-Cu-Fe and Al-Si-Cu-Fe gas-atomized powders to prepare almost pore-free cylindrical specimens with icosahedral and 1/1 cubic approximant phases, respectively. This investigation has revealed that a high density could be obtained despite the short period and low temperature imposed during spark plasma sintering. In comparison to hot press technique, these conditions are favorable since they limit the formation of secondary phases and avoid exaggerated grain growth. The Vickers microhardness and fracture toughness of these two alloy systems were found to be larger than those obtained from cast and hot pressed samples, which could be attributed to a strong bonding between powder particles and the small-grained microstructure of the bulk SPS quasicrystalline specimens.

Spark Plasma Synthesis/Sintering of Dense Ceramic, Intermetallic and Composite Materials

2006 ◽  
Vol 45 ◽  
pp. 1411-1416
Author(s):  
Antonio Mario Locci ◽  
Roberta Licheri ◽  
Roberto Orrù ◽  
A. Cincotti ◽  
Giacomo Cao
Keyword(s):  
Mechanical Load ◽  
Plasma Synthesis ◽  
Simultaneous Application ◽  
Plasma Sintering ◽  
Pulsed Dc ◽  
Spark Plasma ◽  
One Step ◽  
Powder Particles ◽  
Dc Current ◽  
Spark Plasma Synthesis

Spark Plasma Sintering (SPS) represents a very attractive technique for the obtainment of dense materials including nanostructured ones. SPS basically consists in the simultaneous application of a pulsed DC current and an uniaxial mechanical load through a powder compact. Other than providing rapid Joule heating and likely enhancing mass transport through electromigration, the imposed pulsed high current is also reported to generate a plasma within the voids surrounding the powder particles, thus facilitating the removal of oxides surface layers that may hinder the sintering process. Selected results obtained through SPS in our laboratory for the preparation of a wide variety of materials, i.e. TiC-TiB2, MgB2, and NbAl3, will be presented in this work. Specifically, all the chosen examples are related to the use of the SPS technique for obtaining the desired material by simultaneously performing synthesis and consolidation stages in one-step.

Nanoindentation Characterization of Mechanically Alloyed Fe-Al-Si Powders

2018 ◽  
Vol 784 ◽  
pp. 15-20 ◽  
Author(s):  
Petr Haušild ◽  
Jaroslav Čech ◽  
Miroslav Karlík ◽  
Filip Průša ◽  
Pavel Novák ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Preparation Technique ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Microstructure And Mechanical Properties ◽  
Plasma Sintering ◽  
Special Sample Preparation ◽  
Spark Plasma ◽  
Powder Particles

The effect of processing conditions on microstructure and mechanical properties of Fe-Al-Si powders was studied by means of scanning electron microscopy, X-ray diffraction and nanoindentation. Fe-Al-Si alloy powder was prepared from pure elemental powders by mechanical alloying. Microstructure and mechanical properties of powders were characterized after various durations of mechanical alloying. Special sample preparation technique was developed allowing to characterize the properties of individual powder particles after each step of processing in a planetary ball mill. This step-by-step characterization allowed to find the optimum conditions for subsequent spark plasma sintering.

Electric pulse consolidation: an alternative to spark plasma sintering

2013 ◽  
Vol 49 (3) ◽  
pp. 952-985 ◽  
Author(s):  
M. S. Yurlova ◽  
V. D. Demenyuk ◽  
L. Yu. Lebedeva ◽  
D. V. Dudina ◽  
E. G. Grigoryev ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Electric Pulse ◽  
Plasma Sintering ◽  
Spark Plasma

Study on Mechanical Alloying of TiB2 Particulate Reinforced Titanium Matrix Composites

2018 ◽  
Vol 875 ◽  
pp. 41-46 ◽  
Author(s):  
Yue Ying Li ◽  
Fu Wen Zhu ◽  
Zhen Liang Qiao
Keyword(s):  
Mechanical Alloying ◽  
Milling Time ◽  
Volume Fraction ◽  
Matrix Composites ◽  
Titanium Matrix ◽  
Titanium Matrix Composites ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Powder Particles ◽  
Particulate Reinforced

TiB2 particulate reinforced titanium matrix composites were prepared by mechanical alloying and spark plasma sintering. Volume fraction of TiB2 powders in the composites are 5%, 10%, 15%. The effect of milling time and the volume fraction of reinforcement on microstructure and properties of the composites were studied. The results show that with increasing milling time, the size of powder particles decreases, quantity of them increases, and microstructure of the sintered samples becomes finer and more uniform. When milling time reaches 30h, the trend of powder agglomeration increases, the downward trend of the particle size becomes slowly. With the milling time, the density of titanium matrix composites is on the rise. The density of 10vol%TiB2 particulate reinforced titanium matrix composites can reach 4.799 g/cm3, with 30h milling time and sintering at 900°C. The density and hardness of the composites increase with increasing the volume fraction of TiB2. When the volume fraction of TiB2 is 15%, after milling 10h and sintered at 800°C, the density and hardness of the composites can reach 4.713g/cm3 and HV851.58.

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