INFLUENCE OF RAPID QUENCHING AND SAMPLE TREATMENT ON THE STRUCTURE OF MELT SPUN Al-Si ALLOYS

1985 ◽  
Vol 46 (C8) ◽  
pp. C8-533-C8-537
Author(s):  
J. Chevrier ◽  
P. Sainfort ◽  
P. Germi ◽  
D. Pavuna
Keyword(s):  
Rapid Quenching ◽  
Sample Treatment ◽  
Melt Spun

Metastable Phase Transformations in Ti-40Al-10V Alloy

1994 ◽  
Vol 364 ◽  
Author(s):  
G. Shao ◽  
P. Tsakiropoulos ◽  
A. P. Miodownik
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Volume Fraction ◽  
Metastable Phase ◽  
Equilibrium Phase ◽  
Rapid Quenching ◽  
Β Phase ◽  
Transformation Sequence ◽  
Melt Spun ◽  
Melt Spun Ribbons

AbstractThe microstructures in arc melted ingots and melt spun ribbons have been investigated by electron microscopy and thermodynamic modelling has been used to study the phase transformations. In the ingot, solidification starts with the bcc β phase and at room temperature the structure consists of B2, ωordered, γ and α2 phases. The calculated equilibrium phase transformation sequence during cooling is L → L+ β→β→β + α→β2+α → α+β2+γ → α2+γ + B2. The phase transformation sequence is dramatically changed by rapid quenching from the melt. Athermal ordered w phase is formed in metastable B2 and the α→α2 ordering process is completely suppressed in the melt spun ribbons. The volume fraction of the α precipitates is also dependent on cooling rates.

scholarly journals Magnetic properties of ND Rich Melt-Spun ND-FE-B alloy

2005 ◽  
Vol 37 (2) ◽  
pp. 139-145 ◽  
Author(s):  
Aleksandar Grujic ◽  
Nadezda Talijan ◽  
Aleksa Maricic ◽  
Jasna Stajic-Trosic ◽  
Vladan Cosovic ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Measurement ◽  
Rapid Quenching ◽  
Experimental Investigations ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Information ◽  
Melt Spun ◽  
Quenching Process ◽  
Rich Content

As a part of these experimental investigations of melt-spun Nd-Fe-B alloy with Nd rich content in relation to Nd2Fe14B prepared by rapid quenching process for optimally selected cooling rate and heat treatment, the influence of the chosen chemical composition on magnetic properties was observed. The results of X-ray diffraction, M?ssbauer spectroscopy phase analysis and magnetic measurement of investigated melt-spun Nd14.5Fe78.5B7 alloy are presented to bring some new information concerning the relation between their structure and magnetic properties.

Effect of rapid quenching speeds on phase structure and magnetic properties of melt-spun Sm(Co,Fe,Cu,Zr)7.5 ribbons

2009 ◽  
Vol 476 (1-2) ◽  
pp. 575-578 ◽  
Author(s):  
J.B. Sun ◽  
Z.X. Zhang ◽  
C.X. Cui ◽  
W. Yang ◽  
P. Guo ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Phase Structure ◽  
Rapid Quenching ◽  
Melt Spun

The Microstructure of Nb3Al-Mo Intermetallics

1994 ◽  
Vol 364 ◽  
Author(s):  
E. Passa ◽  
P. Tsakiropoulos
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Room Temperature ◽  
Rapid Quenching ◽  
Ternary Alloys ◽  
Complete Solid Solubility ◽  
Melt Spun ◽  
B2 Phase ◽  
Melt Spun Ribbons ◽  
A15 Phase

AbstractThe microstructure of arc melted ingots and melt-spun ribbons of Nb-18A1, Nb-18Al-(20–40) Mo (at%) were studied. Rapid quenching from the melt refined the grain size by at least two orders of magnitude. In the binary alloy ingots and ribbons the Nb3Al (A15) and B2 phases were present. Molybdenum exhibited complete solid solubility in the bcc Nb-Al solid solution as well as in the Nb3Al (A15 phase). The former was the only phase present in the ribbons of the ternary alloys, while Nb3Al was detected only in the ingots. B2 phase was formed in the alloy with 20 at% Mo and the A2 phase was present in the alloy with 40 at% Mo. Furthermore, Mo addition increased the room temperature microhardness of the Nb-Al solid solution by ≈7 Kgmm−2/ at%Mo.

Microstructure of Pitch-Based Carbon Fibers

1980 ◽  
Vol 38 ◽  
pp. 222-223
Author(s):  
C E. Lyman ◽  
T. H. Shen
Keyword(s):  
Carbon Fibers ◽  
High Strain ◽  
Rapid Quenching ◽  
The Other ◽  
Graphitized Carbon ◽  
Anisotropic Liquid ◽  
Isotropic Pitch ◽  
Melt Spun ◽  
Oriented Fiber ◽  
Higher Temperature

Graphitized carbon fibers for use in composite materials have been made from pitch for several years.1,2 Two types of pitch have been used for producing carbon fibers. Aromatic pitch, which is isotropic, needs a high strain rate and rapid quenching to spin into a highly oriented fiber. The other type, known as high molecular weight pitch, forms an anisotropic liquid (mesophase) upon heating and spins at a relatively low speed to form oriented fiber. Usually commercial pitch contains both of these types. The pitch is melt-spun so that the mesophase will form rod-like elongated fibrils embedded in an isotropic matrix. The fiber is oxidized to thermoset the isotropic pitch and then carbonized and graphitized at higher temperature to form a completed 1Oμm diameter carbon fiber.

Study of The Microstructure and Oxidation of NbSi2 Base Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
S.H. Pitman ◽  
P. Tsakiropoulos
Keyword(s):  
Grain Size ◽  
Oxide Scale ◽  
Mixed Oxide ◽  
Rapid Quenching ◽  
Oxidation Behaviour ◽  
Ternary Alloys ◽  
Silica Layer ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Duplex Oxide

AbstractThe microstructures of arc melted ingots and melt spun ribbons of NbSi2 and NbSi2-(8,20 at%)Cr alloys are discussed. Rapid quenching from the melt refined the grain size of the alloys by two orders of magnitude and suppressed the formation of Nb5Si3 in Zone A of the binary alloy ribbons. In the ternary alloy ingots and ribbons formation of the Nb5Si3 was suppressed, and the C40 NbSi2 and CrSi2 and orthorhombic Nb2Si6Cr3 phases were formed. Zone A was not formed in the ribbons of the ternary alloys. The microhardness of these phases and the oxidation behaviour of the alloys up to 1350°C in air and an Ar atmosphere are discussed. NbSi2 did not form a protective silica layer on oxidation. Instead a mixed oxide scale of silica and α-Nb2O5 formed which cracked during growth of the oxide and hindered protection of the alloy. It is shown that the addition of Cr modifies the oxide to a duplex oxide of SiO2 and Cr2O3 and that the underlying matrix becomes depleted in Cr. Pest oxidation at 750°C was suppressed in Nb-60Si-20Cr.

TEM studies of amorphization processes and amorphous structures

1988 ◽  
Vol 46 ◽  
pp. 448-449
Author(s):  
T. E. Mitchell ◽  
R. B. Schwarz
Keyword(s):  
Amorphous Materials ◽  
Fission Products ◽  
Rapid Quenching ◽  
Surface Films ◽  
List Type ◽  
Oxide Glasses ◽  
Crystalline Materials ◽  
Amorphous Structures ◽  
Amorphous Surface ◽  
Interfacial Films

Traditional oxide glasses occur naturally as obsidian and can be made easily by suitable cooling histories. In the past 30 years, a variety of techniques have been discovered which amorphize normally crystalline materials such as metals. These include [1-3]:Rapid quenching from the vapor phase.Rapid quenching from the liquid phase.Electrodeposition of certain alloys, e.g. Fe-P.Oxidation of crystals to produce amorphous surface oxide layers.Interdiffusion of two pure crystalline metals.Hydrogen-induced vitrification of an intermetal1ic.Mechanical alloying and ball-milling of intermetal lie compounds.Irradiation processes of all kinds using ions, electrons, neutrons, and fission products.We offer here some general comments on the use of TEM to study these materials and give some particular examples of such studies.Thin specimens can be prepared from bulk homogeneous materials in the usual way. Most often, however, amorphous materials are in the form of surface films or interfacial films with different chemistry from the substrates.

Microstructural Variations in Melt-Spun Rapidly Solidified Ribbons

1985 ◽  
Vol 43 ◽  
pp. 54-55
Author(s):  
L. A. Bendersky ◽  
W. J. Boettinger
Keyword(s):  
Solid State ◽  
Processing Parameters ◽  
Heat Extraction ◽  
Solid State Reactions ◽  
Careful Examination ◽  
Ion Milling ◽  
Melt Spun ◽  
Wheel Side ◽  
Rapidly Solidified ◽  
Heat Extraction Rate

Rapid solidification produces a wide variety of sub-micron scale microstructure. Generally, the microstructure depends on the imposed melt undercooling and heat extraction rate. The microstructure can vary strongly not only due to processing parameters changes but also during the process itself, as a result of recalescence. Hence, careful examination of different locations in rapidly solidified products should be performed. Additionally, post-solidification solid-state reactions can alter the microstructure.The objective of the present work is to demonstrate the strong microstructural changes in different regions of melt-spun ribbon for three different alloys. The locations of the analyzed structures were near the wheel side (W) and near the center (C) of the ribbons. The TEM specimens were prepared by selective electropolishing or ion milling.

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