TEM Characterization of Two Spark Plasma Sintered Fe-1.5wt.%Mo Steels Stabilized with SiO2 and TiO2

2008 ◽  
Vol 604-605 ◽  
pp. 187-201
Author(s):  
Marcello Cabibbo
Keyword(s):  
Volume Fraction ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Fine Grained Structure ◽  
Spark Plasma ◽  
Boundary Stability

This paper presents a transmission electron microscopy study of two Fe-1.5wt.%Mo steels stabilized with 1.5wt.%SiO2 and 1.5wt.%TiO2,respectively, and compacted through spark plasma sintering. The microstructure inspections revealed that sintered FeMo+SiO2 is able to maintain a nanometric scale grained structure up to a sintering temperature of 815°C, while the steel modified with TiO2 retained its nanometric scale microstructure up to 900°C. The ultra-fine grained structure (within 100-150 nm) was also directly correlated to the grain boundary stability through systematic extinction contours survey. Local nano-welding phenomena shows the effective compacting process of the Fe-Mo powders during sintering. Residual nano-porosity was found to decorate most of the grain boundaries and the triple grain junctions in all the sintering conditions examined, although this nano-porosity accounted for values within 0.26% in volume fraction.

Microstructural Characterization of Fine-Grained Pb(Zr0.52Ti0.48)O3 Ceramics Fabricated by a Spark Plasma Sintering

2006 ◽  
Vol 317-318 ◽  
pp. 155-158
Author(s):  
Sang Mo Koo ◽  
Seung Hwan Shim ◽  
Jong Won Yoon ◽  
Kwang Bo Shim
Keyword(s):  
Spark Plasma Sintering ◽  
Microstructural Characterization ◽  
Structural Features ◽  
Fine Grained ◽  
Domain Structures ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Fine Microstructure ◽  
Spark Plasma

The dense Pb(Zr0.52Ti0.48)O3 (PZT) piezoelectric ceramics have been prepared at a low temperature by a spark plasma sintering (SPS) method without excess PbO addition and their structural features including domains were systematically investigated. The fine microstructure consisting of submicrometer-sized grains as well as relative density reaching 99% was achieved by sintering at 950°C which is 400°C lower than that of pressureless sintering (PLS). Transmission electron microscopy (TEM) results confirmed that the sintered specimen contained very dense domain structures inside each grain, showing the nanoscaled single-domains even at the small grains (below 100 nm). The SPS-processed PZT exhibited better piezoelectric properties than those of the PLS-processed one, which is attributed to its fine-microstructural feature.

The Effect of Preliminary Mechanical Activation on the Structure and Mechanical Properties of Ni3Al+B Material Obtained by SPS

2017 ◽  
Vol 743 ◽  
pp. 19-24 ◽  
Author(s):  
Lilia I. Shevtsova ◽  
Anatoliy A. Bataev ◽  
Vyacheslav I. Mali ◽  
Maksim A. Esikov ◽  
Veronika V. Sun Shin Yan ◽  
...  
Keyword(s):  
Mechanical Activation ◽  
Bending Strength ◽  
Stoichiometric Composition ◽  
Initial Mixture ◽  
Optical Microscope ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Fine Grained Structure ◽  
Spark Plasma ◽  
Almost All

In the present study, a mixture of powders (87.9 at.% Ni, 12 at.% Al, 0.1 at.% B) was used as the initial material to produce sintered Ni3Al + B alloy. Spark Plasma Sintering (SPS) method was used to compact the powder. The powder mixtures were previously prepared in two ways: mixing the initial powders in a mortar (М1) and mechanical activation (М2). The microstructure was observed using optical microscope (OM). The addition of small amount of boron to the initial mixture of nickel and aluminum improves the density of the sintered Ni3Al intermetallic compound (98.8%). The results of density, bending and microhardness tests showed, that the provisional three-minute mechanical activation improves almost all properties of the sintered material. The compact obtained by SPS by M2 contributes to the formation of a homogeneous fine-grained structure of the material. It leads to further increase in flexural bending strength up to 2200 MPa. This value is almost 8 times the strength of the intermetallic Ni3Al stoichiometric composition obtained by SPS.

scholarly journals Fabrication of Porous Materials by Spark Plasma Sintering: A Review

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 541 ◽  
Author(s):  
Dina Dudina ◽  
Boris Bokhonov ◽  
Eugene Olevsky
Keyword(s):  
Porous Materials ◽  
Spark Plasma Sintering ◽  
Sintered Material ◽  
High Rate ◽  
Porous Metals ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Fine Grained Structure ◽  
Spark Plasma ◽  
Pulsed Direct Current

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.

Synthesis of nanostructured metal (Fe, Al)-C60 composites

2010 ◽  
Vol 1276 ◽  
Author(s):  
I. I. Santana García ◽  
V. Garibay Febles ◽  
H. A. Calderon
Keyword(s):  
Raman Spectroscopy ◽  
Mechanical Milling ◽  
Volume Fraction ◽  
High Volume ◽  
X Ray Diffraction ◽  
Nanostructured Composite ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Show Evidence ◽  
Spark Plasma

AbstractComposites of M-2.5 mol. % Fullerene C60 composites (where M= Fe or Al) are prepared by mechanical milling and Spark Plasma Sintering (SPS). The SPS technique has been used to consolidate the resulting powders and preserve the massive nanostructure. Results of X-Ray Diffraction and Raman Spectroscopy show that larger milling balls (9.6 mm in diameter) produce transformation of the fullerene phase during mechanical milling. Alternatively smaller milling balls (4.9 mm in diameter) allow retention of the fullerene phase. SEM shows homogeneous powders with different particle sizes depending on milling times. Sintering produces nanostructured composite materials with different reinforcing phases including C60 fullerenes, diamonds and metal carbides. The presence of each phase depends characteristically on the energy input during milling. Transmission Electron Microscopy (TEM) and Raman Spectroscopy show evidence of the spatial distribution and nature of phases. Diamonds and carbides can be identified for the sintered Fe containing composites with a relatively high volume fraction.

Characterization of Carbon Nanotubes/Cu Nanocomposites Processed by Using Nano-sized Cu Powders

2004 ◽  
Vol 821 ◽  
Author(s):  
Kyung Tae Kim ◽  
Kyong Ho Lee ◽  
Seung Il Cha ◽  
Chan-Bin Mo ◽  
Soon Hyung Hong
Keyword(s):  
Carbon Nanotubes ◽  
Spark Plasma Sintering ◽  
Volume Fraction ◽  
Homogeneous Distribution ◽  
Sintering Process ◽  
Multi Wall Carbon Nanotubes ◽  
Plasma Sintering ◽  
Spark Plasma

AbstractCarbon nanotubes (CNTs) have attracted remarkable attention as reinforcement for composites owing to their outstanding properties1-3. CNT/Cu nanocomposites were fabricated by mixing the nano-sized Cu powders with multi-wall carbon nanotubes and followed by the spark plasma sintering process. The CNT/Cu nanocomposite fabricated from nano-sized Cu powders shows more homogeneous distribution of CNTs in matrix compared to that fabricated from macro-sized Cu powders. The hardness of CNT/Cu nanocomposite fabricated from nano-sized Cu powders increases with increasing the volume fraction of CNTs, while the hardness of that fabricated from macro-sized Cu powders decreases with the addition of CNTs.

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