scholarly journals Rapidly Solidified NiAl and FeAl

1984 ◽  
Vol 39 ◽  
Author(s):  
Darrell J. Gaydosh ◽  
Martin A. Crimp
Keyword(s):  
Heat Treatment ◽  
Grain Growth ◽  
Cleavage Fracture ◽  
Melt Spinning ◽  
Subsequent Heat Treatment ◽  
Transgranular Cleavage ◽  
Intergranular Failure ◽  
Rapidly Solidified ◽  
Bend Ductility

ABSTRACTMelt spinning was used to produce rapidly solidified ribbons of the B2 intermetallics NiAl and FeAl. Both Fe-40Al and Fe-45A1 possessed some bend ductility in the as spun condition. The bend ductility of Fe-40Al, Fe-45Al, and equiatomic NiAl increased with subsequent heat treatment. Heat treatment at approximately 0.85 Tm resulted in significant grain growth in equiatomic FeAl and in all of the NiAl compositions. Low bend ductility in both FeAl and NiAl generally coincided with intergranular failure, while increased bend ductility was characterized by increasing amounts of transgranular cleavage fracture.

Metastable Phases in Rapidly Solidified Aluminum-Rich Al-Fe Alloys

1982 ◽  
Vol 19 ◽  
Author(s):  
D. Shechtman ◽  
L.J. Swartzendruber
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Melt Spinning ◽  
Gamma Ray ◽  
Resonance Spectrum ◽  
Metastable Phase ◽  
Metastable Phases ◽  
Transmission Electron ◽  
Fe Alloys ◽  
Rapidly Solidified

ABSTRACTAluminum-rich Al-Fe binary alloys up to and including Al3Fe were prepared by melt spinning in order to study the metastable phase structure and its transformation following heat treatment. Transmission electron microscopy and nuclear gamma-ray resonance were utilized in the study. The rapidly solidified structure was found to contain up to three metastable phases. One of the phases, with a composition and a gamma-ray resonance spectrum appropriate for Al6Fe, has either a globular or a cellular morphology upon quenching.

Characterization of Melt Spun Cu-Nb Ribbons

1994 ◽  
Vol 362 ◽  
Author(s):  
Mei Ling Henne ◽  
Fereshteh Ebrahimi
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Melt Spinning ◽  
Heat Treatments ◽  
Spherical Particles ◽  
Large Particles ◽  
Melt Spun ◽  
Rapidly Solidified

AbstractMicrostructure of rapidly solidified Cu-5wt%Nb ribbons produced by melt spinning was investigated by SEM and TEM techniques. Two heat treatments were done: 960°C 1 hour and 900° 3 hours. The microstructures contained three different type particles: (a)large particles located at the grain boundary, (b)small spherical particles located within the grains and at the grain boundaries, and (c)fine precipitates formed upon heat treatment. The evolution of the microstructure is discussed with regard to the previously reported studies.

Nanoporous Behavior Induced by Excess Vacancy Clustering in Rapidly-Solidified B2 FeAl Ribbons

2002 ◽  
Vol 753 ◽  
Author(s):  
Tomohide Haraguchi ◽  
Kyosuke Yoshimi ◽  
Man H. Yoo ◽  
Hidemi Kato ◽  
Shuji Hanada ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Concentration Dependence ◽  
Defect Structure ◽  
Melt Spinning ◽  
Volume Fraction ◽  
Excess Vacancy ◽  
Dsc Measurements ◽  
Large Numbers ◽  
Rapidly Solidified ◽  
Nanoporous Surfaces

ABSTRACTRapidly solidified ribbons of B2-ordered Fe-40, 45 and 50mol%Al were produced by a conventional single-roll melt-spinning method. The lattice parameters of as-spun ribbons are fully restored by annealing at 723 K for 24 h. This suggests that large numbers of supersaturated thermal vacancies are removed by the heat treatment. After the heat treatment, it is found that clustering of the supersaturated vacancies leads to a large number of pores that have a few hundreds nm or less in diameter near the surfaces, thus creating nanoporous surfaces. DSC measurements show irreversible exothermic peaks due to vacancy clustering. Vacancy complexes such as dislocations and pores are also observed inside the ribbons by TEM. The volume fraction of the overall vacancy complexes shows Al concentration dependence, demonstrating that defect structure formed by clustering of the excess vacancies is controllable by changing Al concentration in rapidly solidified FeAl ribbons.

EM of rapidly solidified permanent magnets

1992 ◽  
Vol 50 (1) ◽  
pp. 198-199
Author(s):  
Raja K. Mishra
Keyword(s):  
Melt Spinning ◽  
Permanent Magnets ◽  
Dark Field Image ◽  
Dark Field ◽  
Maximum Energy ◽  
Quench Rate ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Annular Dark Field ◽  
Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

Rapidly Solidified Melt-spun Bi-Sn Ribbons: Surface Composition Issues

2016 ◽  
pp. 3287-3297
Author(s):  
Tarek El Ashram ◽  
Ana P. Carapeto ◽  
Ana M. Botelho do Rego
Keyword(s):  
Chemical Composition ◽  
Optical Microscopy ◽  
Melt Spinning ◽  
Surface Composition ◽  
Electrochemical Process ◽  
Melt Spun ◽  
Bismuth Alloy ◽  
The One ◽  
Rapidly Solidified ◽  
Melt Spinning Technique

Tin-bismuth alloy ribbons were produced using melt-spinning technique. The two main surfaces (in contact with the rotating wheel and exposed to the air) were characterized with Optical Microscopy and AFM, revealing that the surface exposed to the air is duller (due to a long-range heterogeneity) than the opposite surface. Also the XPS chemical composition revealed many differences between them both on the corrosion extension and on the total relative amounts of tin and bismuth. For instance, for the specific case of an alloy with a composition Bi-4 wt % Sn, the XPS atomic ratios Sn/Bi are 1.1 and 3.7 for the surface in contact with the rotating wheel and for the one exposed to air, respectively, showing, additionally, that a large segregation of tin at the surface exists (nominal ratio should be 0.073). This segregation was interpreted as the result of the electrochemical process yielding the corrosion products.

An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

2015 ◽  
Vol 10 (2) ◽  
pp. 2663-2681
Author(s):  
Rizk El- Sayed ◽  
Mustafa Kamal ◽  
Abu-Bakr El-Bediwi ◽  
Qutaiba Rasheed Solaiman
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Melt Spinning ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
Microstructural Analysis ◽  
Alloy System ◽  
Antimony Content ◽  
The Stability ◽  
Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as melt–spun ribbons  as a function of antimony content .The stability  of these structures has  been  related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition.  The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes. 

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