scholarly journals Interfacial Reactions between Alumina and Carbon Refractories and Molten Iron at 1,823 K

2016 ◽  
Vol 35 (9) ◽  
pp. 895-904
Author(s):  
Muhammad Ikram-ul-Haq ◽  
Rita Khanna ◽  
Veena Sahajwalla
Keyword(s):  
Phenol Formaldehyde ◽  
Intermetallic Phase ◽  
Argon Atmosphere ◽  
Molten Iron ◽  
Simultaneous Presence ◽  
X Ray ◽  
Heat Treated ◽  
Synthetic Graphite ◽  
Temperature Interactions ◽  
Refractory Degradation

AbstractHigh temperature interactions of alumina–carbon refractories with molten iron were investigated at 1,823 K in argon atmosphere. These studies were specifically focussed on the decomposition of alumina in the simultaneous presence of carbon and iron, and associated refractory degradation. Refractory mixtures were prepared by blending 90 wt% alumina with 10 wt% synthetic graphite; 5–15 wt% iron powder was then mixed with the refractory mixture. Using phenol formaldehyde as a binder, pellets were prepared from various blends; these were heat treated at 1,823 K for 30 min in Ar atmosphere. The presence of molten iron significantly enhanced the decomposition of alumina resulting in an enhanced refractory degradation as well as the formation of a new reactant product. This product was identified as a Fe–Al intermetallic phase from SEM/EDS (scanning electron microscopy/energy-dispersive spectroscopy) and x-ray microdiffraction investigations.

The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

1990 ◽  
Vol 48 (2) ◽  
pp. 442-443
Author(s):  
M. Tamizifar ◽  
G. Cliff ◽  
R.W. Devenish ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Argon Atmosphere ◽  
Age Hardening ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Analytical Electron ◽  
Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

Synthesis of Nano Onion-Like Fullerenes Using Iron Supported on Sodium Chloride as Catalyst by Decomposing Acetylene

2011 ◽  
Vol 393-395 ◽  
pp. 370-372
Author(s):  
Cun Jing Wang ◽  
Peng Yao ◽  
Gai Rong Chen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Sodium Chloride ◽  
Catalytic Decomposition ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Scanning Electron

Catalytic decomposition of acetylene was carried out at 400 °C using iron supported on sodium chloride as catalyst and the product was heat-treated at 650 °C under an argon atmosphere for 2 h directly. The sample was examined by scanning electron microscopy, high resolution transmission electron microscopy and X-ray diffraction. The results show that nano onion-like fullerenes encapsulating Fe cores with diameters in the range 20-50 nm were obtained.

The Transformation of Co-Rich Alloys Produced by Mechanical Alloying

2006 ◽  
Vol 509 ◽  
pp. 135-140
Author(s):  
Francisco Cruz-Gandarilla ◽  
R. Gayosso-Armenta ◽  
J. Gerardo Cabañas-Moreno ◽  
Heberto Balmori-Ramírez
Keyword(s):  
Single Phase ◽  
Intermetallic Phase ◽  
High Energy ◽  
Inert Atmosphere ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Powder Mixtures ◽  
X Ray ◽  
Heat Treated ◽  
Energy Ball

Elemental powder mixtures of Co and Ti were subjected to high-energy ball milling in order to produce mechanically alloyed powders with nominal compositions Co64Ti36, Co67Ti33, Co70Ti30, Co73Ti27, Co76Ti24 and Co85Ti15. The mechanically alloyed powders were treated during 30 minutes in inert atmosphere at temperatures in the range 300 – 700 °C. Both the as-milled powders as well as those subjected to heat treatments have been characterized by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectrometry and differential thermal analysis. As-milled products consist mostly of agglomerated powders with a size between 10 and 80 µm which give an amorphous-like diffraction pattern, except for the Co85Ti15 sample whose pattern presents the characteristic peaks of the Co3Ti intermetallic phase. The transformation of the asmilled powders occurs at temperatures in the range of about 530 – 670 °C with clearly observed exothermic events. The Co3Ti phase is found in all heat treated samples, together with fcc-Co (in Co76Ti24 and Co85Ti15) or the hexagonal Co2Ti intermetallic phase (in Co64Ti36, Co67Ti33 and Co70Ti30); the Co73Ti27 sample was essentially single-phase Co3Ti after heating to 700 °C. Our results suggest the occurrence of crystallization of an amorphous phase in two overlapping stages during heating of the mechanically alloyed powders.

The Electrical Resistivity of B4C Modified Phenol-Formaldehyde Resin Matrix Composite Materials Pyrolyzed at Different Temperatures

2012 ◽  
Vol 583 ◽  
pp. 36-39 ◽  
Author(s):  
Hai Yun Jiang ◽  
Ji Gang Wang ◽  
Shen Qing Wu ◽  
Wei Li Zhang
Keyword(s):  
Electrical Resistivity ◽  
Phenol Formaldehyde ◽  
Phenol Formaldehyde Resin ◽  
Resin Matrix ◽  
Formaldehyde Resin ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Different Temperatures ◽  
Resin Matrix Composite

The electrical resistivity is studied when B4C modified phenol-formaldehyde (PF) resin is heat-treated at temperatures of 300-1500 °C, and then the X-ray diffraction (XRD) spectra are also investigated. The results indicate that the electrical resistivity is elevated with the increase of pyrolytic temperature of PF resin. The addition of B4C decreases the electrical resistivity efficiently when the temperature is range of 700-1000 °C. Especially the composite is treated at tmperatures of 1000-1500 °C. The analysis of XRD spectra suggests that the addition of B4C promotes the arrangement of residue at high temperature. The arrangement reaction has not a direct effect on the electrical resistivity.

Microstructural Characterization of Equiatomic NiTi Alloy Prepared by High Energy Milling

2006 ◽  
Vol 530-531 ◽  
pp. 53-58 ◽  
Author(s):  
Maria do Carmo Silva ◽  
Ana Cris R. Veloso ◽  
Rodinei Medeiros Gomes ◽  
Severino Jackson Guedes de Lima ◽  
Tadeu Antonio de Azevedo Melo ◽  
...  
Keyword(s):  
Room Temperature ◽  
Milling Time ◽  
Niti Alloy ◽  
Microstructural Characterization ◽  
High Energy ◽  
Argon Atmosphere ◽  
Powder Morphology ◽  
X Ray ◽  
Heat Treated

NiTi alloys with equiatomic composition of NiTi have the highest technological interest for its potencial application in differents areas such as biomedical, naval, aerospace, nuclear, automobilist , robotic,etc. In this work , it was used a 50Ni50Ti at % powder mixture, comercially pure, prepared by mechanical alloying in a Attritor with the following conditions: the milling speed and the ball charge were 1500 rpm and 10:1 respectively. The milling time was 2,4,8 and 16h, under an argon atmosphere at room temperature. After milling it was determined the particle size distribution, the phases by X-ray diffractions (XRD) and the powder morphology by scanning electron microscopy (SEM). The milling promotes dissolution of Titanium in Nickel and continuous amorphization by increasing the milling time. After 16h milling the alloy was almost amorphous. The powders after milling were compacted and heat treated at high temperature and microstructural evolution was characterized. In the heat treated samples were detected different phases showing heterogeneity in the alloy. The detected phases were Ni3Ti, NiTi, Ni2Ti and Ni2Ti4O. Contamination by milling was detected in the powder after milling and in the heat treated samples.

scholarly journals TEM study of precipitation in a Nial-3Ti-0.5Hf single-crystal alloy

1996 ◽  
Vol 54 ◽  
pp. 998-999
Author(s):  
A. Garg ◽  
R. D. Noebe ◽  
J. M. Howe ◽  
A. W. Wilson ◽  
V. Levit
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Single Crystal ◽  
Argon Atmosphere ◽  
Second Phase ◽  
Directionally Solidified ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated

Three directionally solidified NiAl single-crystal alloys, NiAl-3Ti, NiAl-0.5Hf and NiAl-3Ti-0.5Hf (at.%), were grown by a Bridgeman technique using high purity alumina crucibles. The ingots were homogenized for 32h at 1644 K followed by aging for 6h at 1255 K and finally furnace cooled under an argon atmosphere. This heat treatment was found to be very effective in dissolving Hf-rich interdendritic particles that were present in the as-cast structure, and at the same time it produced fine second-phase precipitates in the alloy.Samples for transmission electron microscopy (TEM) were prepared from 3 mm diameter cylinders electro-discharge machined from the heat-treated ingots. Slices sectioned from the cylinders were mechanically ground and electrochemically thinned in a twin-jet Tenupol-3 polisher. Microstructural and energy-dispersive X-ray spectroscopy (EDXS) studies were conducted in a Philips 400T TEM equipped with a double tilt goniometer and a KEVEX Si/Li X-ray detector.

Preparation of Ta-12.5Si-25B Powders by Mechanical Alloying

2006 ◽  
Vol 530-531 ◽  
pp. 197-202 ◽  
Author(s):  
Alfeu Saraiva Ramos ◽  
Erika Coaglia Trindade Ramos ◽  
Carlos de Moura Neto
Keyword(s):  
Heat Treatment ◽  
Ball Milling ◽  
Room Temperature ◽  
Intermetallic Phase ◽  
Milling Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unknown Phase ◽  
Heat Treated ◽  
Equilibrium Microstructure

The present work reports on the preparation of the Ta5SiB2 compound by highenergy ball milling and subsequent heat treatment from elemental Ta-12.5at%Si-25at%B powder mixture. The milling process was carried out at room temperature in a planetary ball mill under argon atmosphere. Following the milling process, the powders were heat-treated at 1200oC for 4h under Ar atmosphere in order to obtain the equilibrium microstructure. The milled and heat-treated powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated that the Si peaks disappeared after milling for 1h. It was noted that the broadening and the reduced intensity of Ta peaks occurred continuously up to milling for 10h, suggesting that the Si and B atoms were preferentially dissolved into the Ta lattice during ball milling to form a supersaturated solid solution. A halo was formed in Ta-12.5at%Si-25at%B powders milled for 100h, suggesting that an amorphous phase was achieved. No intermetallic phase was formed in powders milled for 200h. A large amount of Ta5SiB2 was formed after heat treatment at 1200oC for 4h. In addition, peaks of TaB and another unknown phase were also identified.

Direct Observation of Crystalline Ordering In Naturally Graphitized Carbon Produced by Low Grade Metamorphism

1977 ◽  
Vol 35 ◽  
pp. 162-163
Author(s):  
Thomas R. McKee ◽  
Peter R. Buseck
Keyword(s):  
Crystallite Size ◽  
Sedimentary Rocks ◽  
Carbonaceous Material ◽  
Low Grade ◽  
X Ray ◽  
Graphitized Carbon ◽  
Transmission Electron ◽  
Heat Treated ◽  
Commercial Carbon ◽  
Metamorphic Zone

Sediments commonly contain organic material which appears as refractory carbonaceous material in metamorphosed sedimentary rocks. Grew and others have shown that relative carbon content, crystallite size, X-ray crystallinity and development of well-ordered graphite crystal structure of the carbonaceous material increases with increasing metamorphic grade. The graphitization process is irreversible and appears to be continous from the amorphous to the completely graphitized stage. The most dramatic chemical and crystallographic changes take place within the chlorite metamorphic zone.The detailed X-ray investigation of crystallite size and crystalline ordering is complex and can best be investigated by other means such as high resolution transmission electron microscopy (HRTEM). The natural graphitization series is similar to that for heat-treated commercial carbon blacks, which have been successfully studied by HRTEM (Ban and others).

Long-period modulated superstructures in Pd-12.5 at.%Ce and Pd-15 at.%Ce alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 164-165
Author(s):  
Noriyuki Kuwano ◽  
Masaru Itakura ◽  
Kensuke Oki
Keyword(s):  
Electron Microscopy ◽  
Mean Value ◽  
Heavy Elements ◽  
Arc Furnace ◽  
X Ray ◽  
Long Period ◽  
Ultra High Purity ◽  
Heat Treated ◽  
Atomic Scattering ◽  
The Mean

Pd-Ce alloys exhibit various anomalies in physical properties due to mixed valences of Ce, and the anomalies are thought to be strongly related with the crystal structures. Since Pd and Ce are both heavy elements, relative magnitudes of (fcc-fpd) are so small compared with <f> that superlattice reflections, even if any, sometimes cannot be detected in conventional x-ray powder patterns, where fee and fpd are atomic scattering factors of Ce and Pd, and <f> the mean value in the crystal. However, superlattices in Pd-Ce alloys can be analyzed by electron microscopy, thanks to the high detectability of electron diffraction. In this work, we investigated modulated superstructures in alloys with 12.5 and 15.0 at.%Ce.Ingots of Pd-Ce alloys were prepared in an arc furnace under atmosphere of ultra high purity argon. The disc specimens cut out from the ingots were heat-treated in vacuum and electrothinned to electron transparency by a jet method.

scholarly journals Stable and Metastable Phase Equilibria Involving the Cu6Sn5 Intermetallic

2021 ◽  
Author(s):  
A. Leineweber ◽  
M. Löffler ◽  
S. Martin
Keyword(s):  
Phase Equilibria ◽  
Electron Backscatter Diffraction ◽  
Metastable Phase ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Ordered Phases ◽  
Backscatter Diffraction ◽  
Kinetics Of

Abstract Cu6Sn5 intermetallic occurs in the form of differently ordered phases η, η′ and η′′. In solder joints, this intermetallic can undergo changes in composition and the state of order without or while interacting with excess Cu and excess Sn in the system, potentially giving rise to detrimental changes in the mechanical properties of the solder. In order to study such processes in fundamental detail and to get more detailed information about the metastable and stable phase equilibria, model alloys consisting of Cu3Sn + Cu6Sn5 as well as Cu6Sn5 + Sn-rich melt were heat treated. Powder x-ray diffraction and scanning electron microscopy supplemented by electron backscatter diffraction were used to investigate the structural and microstructural changes. It was shown that Sn-poor η can increase its Sn content by Cu3Sn precipitation at grain boundaries or by uptake of Sn from the Sn-rich melt. From the kinetics of the former process at 513 K and the grain size of the η phase, we obtained an interdiffusion coefficient in η of (3 ± 1) × 10−16 m2 s−1. Comparison of this value with literature data implies that this value reflects pure volume (inter)diffusion, while Cu6Sn5 growth at low temperature is typically strongly influenced by grain-boundary diffusion. These investigations also confirm that η′′ forming below a composition-dependent transus temperature gradually enriches in Sn content, confirming that Sn-poor η′′ is metastable against decomposition into Cu3Sn and more Sn-rich η or (at lower temperatures) η′. Graphic Abstract

Sign in / Sign up

Export Citation Format

Share Document