The use of rapid solidification processes in search of new hard magnetic materials

1987 ◽  
Vol 65 (10) ◽  
pp. 1200-1209 ◽  
Author(s):  
G. C. Hadjipanayis
Keyword(s):  
Magnetic Materials ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
Size Range ◽  
Amorphous Structure ◽  
Hard Magnetic Materials ◽  
Fine Grained ◽  
Solidification Processes ◽  
Cast Alloys ◽  
Melt Spinning Technique

Rapid solidification can be used to prepare amorphous and other metastable phases and special microstructures that cannot be obtained otherwise. The melt-spinning technique has been used for R15Fe77B8 and SmCo5−xNix alloys in a search for new hard magnetic materials. In R15Fe77B8, the as-quenched samples had an amorphous structure that on heating, crystallized into a fine-grained microstructure with R2Fe14B as the major phase. The grain-size range was 200–4000 Å, leading to coercivities that were much higher than those in sintered magnets. In SmCo5−xNix, melt-spinning produced both a fine-grained microstructure and a higher degree of atomic disorder, leading to substantially higher coercivity than was obtained in as-cast alloys.

scholarly journals The Influence of Heat Treatment on the Phase Structure of the Nanocrystalline (Nd10Fe67B23)95Nb5 Alloy Ribbons

2020 ◽  
Vol 70 (12) ◽  
pp. 4450-4454
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Magnetic Materials ◽  
Phase Structure ◽  
Melt Spinning ◽  
Nanocrystalline Structure ◽  
Cast State ◽  
Hard Magnetic Materials ◽  
Mössbauer Studies ◽  
Melt Spinning Technique

The main goal of present paper was to study of phase composition of nanocrystalline (Nd10Fe67B23)95Nb5 ribbons prepared by melt-spinning technique with different velocity of the copper wheel. Samples in the as-cast state obtained using speed 5 and 10 m/s had nanocrystalline structure. In case of samples prepared by with speed of copper Wheel 15 and 35 m/s were fully amorphous. In the DSC curve, the two minima corresponding to crystallization of the Nd2Fe23B3 and Nd2Fe14B phases were detected. The coexistence of three phases: Nd2Fe14B, Nd2Fe23B3 and Nd1+εFe4B4 were detected. Higher temperatures of annealing caused crystallization of α-Fe phase. The XRD results were confirmed by the Mössbauer studies. Keywords: hard magnetic materials, phase structure, Mössabuer spectroscopy

Giant Magnetoimpedance in as Quenched Fe Based Nanocrystalline Ribbons

2005 ◽  
Vol 475-479 ◽  
pp. 2219-2222 ◽  
Author(s):  
Ji Fan Hu ◽  
Hong Wei Qin ◽  
Minhua Jiang ◽  
Bo Li ◽  
Dongliang Zhao ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Materials ◽  
Melt Spinning ◽  
Experimental Results ◽  
Soft Magnetic Materials ◽  
Soft Magnetic ◽  
Giant Magnetoimpedance ◽  
Giant Magnetoimpedance Effect ◽  
Additional Annealing ◽  
Melt Spinning Technique

FeCuNbSiB and FeZrBCu nanocrystalline ribbons can be obtained directly through the melt- spinning technique without additional annealing processes. The giant magnetoimpedance can be observed in FeCuNbSiB and FeZrBCu as quenched ribbons. The addition of Cu improves the nano-crystallization of a-Fe(Si) or a-Fe phase and reduces the grain size in FeCuNbSiB and FeZrBCu as quenched ribbons, which enhances the magnetoimpedance via increasing the variation of permeability under fields. The present experimental results reveal a novel route to fabricate the Fe based nanocrystalline soft magnetic materials with giant magnetoimpedance effect.

Enhanced Electrochemical Hydrogen Storage Characteristics of Mg2Ni-Type Alloy by Substituting Mg with La

2011 ◽  
Vol 399-401 ◽  
pp. 1461-1466
Author(s):  
Hui Ping Ren ◽  
Bao Wei Li ◽  
Yin Zhang ◽  
Zai Guang Pang ◽  
Zhong Hui Hou ◽  
...  
Keyword(s):  
Melt Spinning ◽  
Amorphous Structure ◽  
High Rate ◽  
Electrochemical Performances ◽  
Type Alloy ◽  
Major Phase ◽  
Nanocrystalline And Amorphous ◽  
Ni Alloy ◽  
Electrochemical Hydrogen Storage ◽  
Cast Alloys

The melt-spinning technique is applied to the preparation of the nanocrystalline and amorphous Mg2Ni-type alloys with nominal compositions of Mg2-xLaxNi (x=0, 0.2, 0.4, 0.6). The as-spun alloy ribbons possessing a continuous length, a thickness of about 30 μm and a width of about 25 mm were prepared. The structures of the as-spun alloy ribbons are characterized by XRD, SEM and TEM. The electrochemical performances of the as-spun alloy ribbons are measured by an automatic galvanostatic system. The results show that no amorphous structure is detected in the as-spun Mg2Ni alloy, whereas the as-spun alloys substituted by La display a nanocrystalline and amorphous structure, confirming that the substitution of La for Mg notably intensifies the amorphous forming ability of the Mg2Ni-type alloy. For La content x≤0.2, the substitution of La for Mg brings to the formation of LaMg3 and La2Mg17 phases without changing the Mg2Ni major phase. But as La content is increased to x≥0.4, such substitution changes the major phase of the alloys to (La, Mg)Ni3+LaMg3. The discharge capacity of the as-cast alloys grows with the increasing amount of La substitution, whereas that of the as-spun alloys yields a maximum value with variation of La content. Furthermore, the substitution of La for Mg remarkably enhances the cycle stability of the as-cast and spun alloys. And the high rate dischargeability (HRD) of the as-cast and spun alloys first mounts up then falls with rising La content.

scholarly journals MICROSTRUCTURE AND THERMAL STABILITY OF Al-Fe-X ALLOYS

2018 ◽  
Vol 24 (3) ◽  
pp. 223 ◽  
Author(s):  
Andrea Školáková ◽  
Petra Hanusová ◽  
Filip Průša ◽  
Pavel Salvetr ◽  
Pavel Novák ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Melt Spinning ◽  
Hot Extrusion ◽  
Dispersed Particles ◽  
Cast Alloys ◽  
Rapidly Solidified ◽  
Thermal Stability Of ◽  
Melt Spinning Technique ◽  
Extrusion Method

<p>In this work, Al-11Fe, Al-7Fe-4Ni and Al-7Fe-4Cr (in wt. %) alloys were prepared by combination of casting and hot extrusion. Microstructures of as-cast alloys were composed of aluminium matrix with large and coarse intermetallics such as Al<sub>13</sub>Fe<sub>4</sub>, Al<sub>13</sub>Cr<sub>2</sub> and Al<sub>5</sub>Cr. Subsequently, as-cast alloys were rapidly solidified by melt-spinning technique which led to the supersaturation of solid solution alloying elements. These rapidly solidified ribbons were milled and compacted by hot-extrusion method. Hot-extrusion caused that microstructures of all alloys were fine with uniform dispersed particles. Moreover, long-term thermal stability was tested at temperature 300 °C for as-cast and hot-extruded alloys and chromium was found to be the most suitable element for alloying to improve thermal stability.    </p>

Structure and thermal behavior of lead-free solders prepared by rapid solidification of their melt

2017 ◽  
Vol 29 (1) ◽  
pp. 49-53 ◽  
Author(s):  
Martin Durisin ◽  
Alena Pietrikova ◽  
Juraj Durisin ◽  
Karel Saksl
Keyword(s):  
Thermal Stability ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
Lead Free ◽  
Content Type ◽  
Intermetallic Particles ◽  
Lead Free Solders ◽  
Practical Implications ◽  
Thermal Stability Of ◽  
Melt Spinning Technique

Purpose The paper aims to investigate the structure and thermal stability of newly developed lead-free Sn-based alloys which can be used as novel materials in the soldering of electronic components. Design/methodology/approach Rapid solidification was used to prepare the alloys. Findings The results showed that the microstructure of these solders exhibited uniform distribution and small-sized intermetallic compounds. Also, smaller crystalline size can be expected compared to commercially available counterparts. The analyses revealed a uniform and homogenous distribution of the small intermetallic particles of Cu6Sn5 and Ag4Sn in the microstructure of solders. The practical implications mean an improvement in mechanical properties and thermal stability of such solder joints, which is a precondition of low mechanical, thermo-mechanical stresses in their structure. Originality/value The originality lies in the production of these alloys by the melt spinning technique which was not previously used in the electronics industry.

Magnetic and Magneto-Optical Research of Ni43.7Mn43.6In12.7 Ribbons

2015 ◽  
Vol 233-234 ◽  
pp. 200-203 ◽  
Author(s):  
Andrey Novikov ◽  
Elena Gan’shina ◽  
Lorena Gonzalez-Legarreta ◽  
V.M. Prida ◽  
Blanca Hernando ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Chemical Composition ◽  
Martensitic Transformation ◽  
Energy Range ◽  
Rapid Solidification ◽  
Kerr Effect ◽  
Melt Spinning ◽  
Spectral Energy ◽  
The Difference ◽  
Melt Spinning Technique

We report the magnetic and magneto-optical (MO) properties of the Heusler Ni43.7Mn43.6In12.7 alloy ribbon in martensitic and austenitic states. The samples were produced by rapid solidification using the melt-spinning technique. The difference between the transformation temperatures obtained from magnetization and transverse Kerr effect (TKE) measurements shows that the chemical composition and/or microstructure are not identical in the bulk and at the ribbon surface. The TKE spectra profile in the spectral energy range of 0.5-3.5 eV does not change significantly at the martensitic transformation that indicates on a very similar electronic structure in martensitic and austenitic states.

Effect of Crystallization on the Electrical Resistance and Structure of Amorphous Fe-Co-Cr-B-Si Alloys / Wpływ Krystalizacji Na Oporność Elektryczną I Strukturę Amorficznych Stopów Fe-Co-Cr-B-Si

2012 ◽  
Vol 57 (4) ◽  
pp. 1031-1039
Author(s):  
H. Solomon ◽  
N. Solomon
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Amorphous Alloys ◽  
Melt Spinning ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Investigation Methods ◽  
Melt Spinning Technique

The goal of this paper is to present the influence of temperature variation and iron substitution with Co on the structure and electrical properties of amorphous Fe75-xCoxCr1B7Si17 alloys (where x=1, 4, 7, and 10 at.%), obtained by melt-spinning technique. The electrical resistivity of the samples was measured by using a usual four-probe method from -160°C to 750°C. The electrical resistivity was also measured at room temperature for the amorphous Fe75-xCoxCr1B7Si17 ribbons annealed at various temperatures for different holding time. The annealed samples were also investigated by Vickers microhardness test. The amorphous structure of tested materials was examined by X-ray diffraction (XRD), Mossbauer spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) methods. Experimental results confirmed the utility of applied investigation methods and the influence of the Co content and annealing process on the crystallization, structure and electrical properties of examined amorphous alloys.

The effect of rapid solidification and grain size on the transformation temperatures of Ni-44,8wt%Ti melt spun alloy

2012 ◽  
Vol 1373 ◽  
Author(s):  
G. C. S. Anselmo ◽  
W. B. de Castro ◽  
C. J. de Araújo
Keyword(s):  
Differential Scanning Calorimetry ◽  
Grain Size ◽  
Martensitic Transformation ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
Scanning Calorimetry ◽  
Transformation Temperatures ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Melt Spinning Technique

ABSTRACTRibbons of the Ni-44.8wt%Ti shape memory alloy are prepared through the melt spinning technique. The study is focused on investigating the effect of the rapid solidification and grain size at characteristic start martensitic (Ms), final martensitic (Mf), start austenite (As) and final austenite (Af) transformation temperatures. Changes on martensitic transformation temperatures in Ti45Ni55 melt spun ribbons are observed as grain size is reduced. Results of optical microscopy and differential scanning calorimetry (DSC) are used to associate grain size with transformation temperatures.

Interfacial structures of dissimilar materials joined by capacitor-discharge welding

1994 ◽  
Vol 52 ◽  
pp. 534-535
Author(s):  
C. P. Doğan ◽  
R. D. Wilson ◽  
J. A. Hawk
Keyword(s):  
Rapid Solidification ◽  
Fusion Zone ◽  
Dissimilar Materials ◽  
Solidification Process ◽  
Weld Interface ◽  
Capacitor Discharge ◽  
Fine Grained ◽  
Iron Aluminum ◽  
Conductive Ceramics ◽  
Capacitor Discharge Welding

Capacitor Discharge Welding is a rapid solidification technique for joining conductive materials that results in a narrow fusion zone and almost no heat affected zone. As a result, the microstructures and properties of the bulk materials are essentially continuous across the weld interface. During the joining process, one of the materials to be joined acts as the anode and the other acts as the cathode. The anode and cathode are brought together with a concomitant discharge of a capacitor bank, creating an arc which melts the materials at the joining surfaces and welds them together (Fig. 1). As the electrodes impact, the arc is extinguished, and the molten interface cools at rates that can exceed 106 K/s. This process results in reduced porosity in the fusion zone, a fine-grained weldment, and a reduced tendency for hot cracking.At the U.S. Bureau of Mines, we are currently examining the possibilities of using capacitor discharge welding to join dissimilar metals, metals to intermetallics, and metals to conductive ceramics. In this particular study, we will examine the microstructural characteristics of iron-aluminum welds in detail, focussing our attention primarily on interfaces produced during the rapid solidification process.

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