Formation of Quasicrystals In Rapidly Solidified Al Alloys

ABSTRACTElectron beam surface melting has been used to study Al-Mn and Al-Mn-Si alloys subjected to a wide range of solidification conditions. Several of the reported equilibrium intermetallic phases are not found even at moderate growth rates. Beyond a composition-dependent critical velocity the equilibrium phases are all replaced by the quasicrystalline icosahedral and decagonal (T) phases. The icosahedral phase is favored over the T phase by higher solidification velocities. The addition of Si to Al-Mn alloys eliminates the T phase, but does not significantly facilitate the formation of the icosahedral phase by electron beam melting because the ternary α and β phases of Al-Mn-Si are able to grow rapidly into the electron beam melts.

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STRUCTURE AND MECHANICAL PROPERTIES OF ALUMINIUM ALLOYS RAPIDLY SOLIDIFIED BY ELECTRON BEAM SURFACE TREATMENT

Rapidly Quenched Metals ◽

10.1016/b978-0-444-86939-5.50223-2 ◽

1985 ◽

pp. 937-940

Author(s):

Bernard VINET ◽

Serge PAÏDASSI

Keyword(s):

Mechanical Properties ◽

Electron Beam ◽

Surface Treatment ◽

Aluminium Alloys ◽

Beam Surface ◽

Rapidly Solidified

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Synthesis of Hard-Melting Carbide, Nitrite and Intermetallic Phases with Surface Electron-Beam Microallоying

Materials Science Forum ◽

10.4028/www.scientific.net/msf.876.25 ◽

2016 ◽

Vol 876 ◽

pp. 25-35 ◽

Cited By ~ 1

Author(s):

Mariuch Jenek ◽

Sergey Voldemarovich Fedorov ◽

Min Htet Swe

Keyword(s):

Thin Film ◽

Electron Beam ◽

Chemical Reactions ◽

Intermetallic Phases ◽

Experimental Results ◽

Reaction Products ◽

Surface Electron ◽

Wide Range ◽

New Phase

The experimental results prove the ability to produce layers modified by microalloying with electron-beam technology using wide range of materials. Such layers were produced due to initiating exothermic chemical reactions between the base and the thin film covered the base. This resulted in finding new phase compounds in reaction products.

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Surface Alloys of Icosahedral AlMnSi with Phason Distortions

MRS Proceedings ◽

10.1557/proc-74-333 ◽

1986 ◽

Vol 74 ◽

Cited By ~ 3

Author(s):

D. M. Follstaedt ◽

J. A. Knapp

Keyword(s):

Electron Beam ◽

Electron Beam Melting ◽

Ion Beam ◽

Icosahedral Phase ◽

The Novel ◽

Ion Beam Mixing ◽

Si Substrates ◽

Formation Kinetics ◽

Icosahedral Phases ◽

Diffraction Patterns

AbstractThe microstructures produced by electron-beam melting and by ion-beam mixing Al/Mn and Al/Mn/Si layers on Si substrates are examined. The treatments were found to incorporate Si from the substrate into the surface alloy. Several phases formed, depending on treatment, including α- and β-AlMnSi, μ-AlMn (epitaxial on Si{111}), and amorphous and icosahedral AlMnSi. The observed microstructures relate the novel icosahedral phase to other phases and elucidate its formation kinetics. Diffraction patterns from large icosahedral grains (up to 5 μm) show distortions in the position and shape of weak (but not strong) reflections, as predicted for phason defects in a quasicrystalline lattice, one of the structures proposed for icosahedral phases.

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Microstructure and Properties of Mold Steel 3Cr2W8V by Electron Beam Surface Alloying

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.160-162.789 ◽

2010 ◽

Vol 160-162 ◽

pp. 789-795

Author(s):

Yuan Fang Chen ◽

Xiao Dong Peng ◽

Jian Jun Hu ◽

Hong Bin Xu ◽

Chan Hao

Keyword(s):

Surface Roughness ◽

Wear Resistance ◽

Electron Beam ◽

Coating Layer ◽

High Hardness ◽

Surface Alloying ◽

Micro Hardness ◽

Hardness Tester ◽

Beam Surface ◽

Rapidly Solidified

Ti coating was deposited on mold steel 3Cr2W8V by PVD and then processed with electron beam surface alloying process. The microstructure, surface roughness and microhardness of electron beam surface alloying treated specimens were investigated by using metallurgical microscope, SEM , XRD, micro hardness tester and roughness tester. It is shown that the electron beam surface alloying treated specimens have a rapidly solidified microstructure consisting of the uniformly distributed TiC phases and fine VCrFe8 intermetallic phases.The coating has a strong metallurgical boning with substrate, and the coating has high hardness, excellent wear resistance. The coating layer has an average microhardness of approximately HV600, 35% higher than the substrate’s. So it is used widely. Furthermore the need for further research is discussed as well.

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A Color Coded STEM/SEM Image Storage System

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100097880 ◽

1981 ◽

Vol 39 ◽

pp. 272-273

Author(s):

Y. Kokubo ◽

W. H. Hardy ◽

J. Dance ◽

K. Jones

Keyword(s):

Image Processing ◽

Electron Beam ◽

Storage System ◽

Particle Analysis ◽

Specific Information ◽

X Rays ◽

Sem Image ◽

Backscattered Electrons ◽

Wide Range ◽

Scanning Electron

A color coded digital image processing is accomplished by using JEM100CX TEM SCAN and ORTEC’s LSI-11 computer based multi-channel analyzer (EEDS-II-System III) for image analysis and display. Color coding of the recorded image enables enhanced visualization of the image using mathematical techniques such as compression, gray scale expansion, gamma-processing, filtering, etc., without subjecting the sample to further electron beam irradiation once images have been stored in the memory.The powerful combination between a scanning electron microscope and computer is starting to be widely used 1) - 4) for the purpose of image processing and particle analysis. Especially, in scanning electron microscopy it is possible to get all information resulting from the interactions between the electron beam and specimen materials, by using different detectors for signals such as secondary electron, backscattered electrons, elastic scattered electrons, inelastic scattered electrons, un-scattered electrons, X-rays, etc., each of which contains specific information arising from their physical origin, study of a wide range of effects becomes possible.

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