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.

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.

Synthesis and Characterization of Mnbi Magnetic Alloy via Two Different Processing Routes

2021 ◽  
Vol 875 ◽  
pp. 76-80
Author(s):  
Hifsa Mazhar ◽  
Wilayat Hussain
Keyword(s):  
Heat Treatment ◽  
Melt Spinning ◽  
Treatment Time ◽  
Magnetic Energy ◽  
Microstructural Characterization ◽  
Temperature Phase ◽  
Magnetic Alloy ◽  
Positive Temperature ◽  
Melt Spinning Technique

Manganese bismuth alloy has gained importance due to its rare earth free elements, positive temperature coefficient and unique magnetic properties. Low temperature phase (LTP) MnBi was successfully prepared by arc melting with subsequent heat treatments and melt spinning technique followed by heat treatment for different durations. LTP MnBi formation was confirmed using XRD analysis and microstructural characterization of the samples was done using field emission scanning electron microscope. MnBi with greater LTP amount was formed by melt spinning route when compared with its counter arc melted one. Magnetic energy density of LTP MnBi formed by melt spinning technique with different heat treatment time was studied.

Microstructure in Rapidly Quenched Al-Ti,Al-B and Al-Ti-B Alloys

1986 ◽  
Vol 80 ◽  
Author(s):  
A. Majumdar ◽  
R. H. Mair ◽  
B. C. Muddle
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
Primary Phase ◽  
Nucleation Sites ◽  
Uniform Dispersion ◽  
Average Grain Size ◽  
Melt Spun ◽  
Chill Cast

AbstractRapidly quenched ribbons (˜50m thickness) of Al-5wt.%Ti, Al-lwt.%B and a range of Al-Ti-B alloys have been produced by melt spinning under He atmosphere and the microstructures of the ribbons, following solidification and post-solidification heat treatment, characterized using analytical electron microscopy. In the Al-5Ti alloy, the coarse equilibrium primary phase (b.c.t. Al3 Ti) that is observed following conventional casting is replaced by fine (0.1–0. 2μm), cuboidal particles of a metastable cubic (Ll2) Al3Ti in melt-spun ribbon. These metastable particles form directly from the melt and act as nucleation sites for the solid solution which subsequently forms. A refined microstructure with an average grain size of 1–2μm results. A supersaturation of Ti is retained in matrix solid solution following solidification and a variety of solid state precipitate forms, including fine dispersions of coherent, metastable Al3 Ti particles, is observed to emerge during post-solidification heat treatment. For the Al-1B alloy, the coarse distribution of primary AlB2 particles in a chill-cast ingot is replaced by a fine, uniform dispersion of the metastable boride, α-AlB12, in the melt-spun ribbon. Attempts to induce a refined boride dispersion in melt-spun Al-Ti-B alloys have proved largely unsuccessful.

Atomic Scale Characterisation of Electrodeposited Nanocrystalline Ni-P Alloys

1999 ◽  
Vol 581 ◽  
Author(s):  
Matthias Abraham ◽  
Mattias Thuvandert ◽  
Helen M. Lane ◽  
Alfred Cerezo ◽  
George D.W. Smith
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Boundary Segregation ◽  
Atom Probe ◽  
Atomic Scale ◽  
Grain Boundary Segregation ◽  
P Concentration

ABSTRACTNanocrystalline Ni-P alloys produced by electrodeposition have been characterised by three-dimensional atom probe (3DAP) analysis. In the as-deposited materials, there are indications of some variation in P concentration between grains and segregation to grain boundaries. After heat treatment however, strong grain boundary segregation and the formation of Ni3P precipitates have been observed.

Microstructure characterization of one-directionally oriented ulexite

1998 ◽  
Vol 13 (3) ◽  
pp. 778-783 ◽  
Author(s):  
Yumi H. Ikuhara ◽  
Shinji Kondoh ◽  
Koichi Kikuta ◽  
Shin-ichi Hirano
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Small Angle ◽  
Stacking Faults ◽  
Contact Angles ◽  
Light Transmittance ◽  
High Angle ◽  
Electron Dose ◽  
Bundle Structure

Microstructures of ulexite were investigated by CTEM and low electron dose HREM. It was found that the longitudinal grains in ulexite were oriented to c-direction to form a bundle structure. There were a number of small-angle grain boundaries and stacking faults inside a grain in the ulexite. Cleavage microcracks and stacking faults were mostly introduced on the {010} of the ulexite. The high-angle grain boundaries mainly consisted of high coincidence boundaries, which was confirmed by a comparison of observed contact angles and calculated degree of coincidence at the boundaries. The light transmittance properties of the ulexite would depend on the defects such as stacking fault, small-angle grain boundary, and high-angle grain boundary.

Characterization of Intergranular Phases in Doped Zirconia Polycrystals

1999 ◽  
Vol 589 ◽  
Author(s):  
N. D. Evans ◽  
P. H. Imamura ◽  
J. Bentley ◽  
M. L. Mecartney
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Analytical Electron Microscopy ◽  
Tetragonal Zirconia ◽  
Barium Ions ◽  
Analytical Electron ◽  
Scanning Transmission ◽  
Triple Points ◽  
Boundary Chemistry

AbstractAnalytical electron microscopy at high spatial resolution in a scanning-transmission mode has been used to investigate the effects of glassy or crystalline material additions on grain boundary chemistry in yttria-stabilized zirconia polycrystals. Powders of additive phase were mixed into 3-mol% yttria-stabilized tetragonal zirconia polycrystals (‘3Y-TZP’) or 8-mol% yttria-stabilized cubic zirconia polycrystals (‘8Y-CSZ’). Zirconias processed without additive phases were also examinedWithout additives, grain boundaries were depleted in zirconium and enriched in yttrium. In 3Y-TZP with I wt% borosilicate glass, silicon was observed only at triple points, but not in grain boundaries. In 3Y-TZP with 1 wt% barium silicate glass, barium was observed both along grain boundaries and at triple points, whereas silicon was detected only within the triple points. This suggests either the composition of the additive phase at the grain boundary is different from that at the triple points, or that barium ions segregate to grain boundaries during processing. In 8Y-CSZ with I wt% silica, silicon was observed in grain boundaries by an EDS spatial differencing technique. In 8Y-CSZ with 10 wt% alumina, EDS revealed aluminum at all grain boundaries examined

Quantitative Characterization of Grain Boundary Films In Si3n4 by Eels and Z-Contrast Imaging

1997 ◽  
Vol 3 (S2) ◽  
pp. 661-662
Author(s):  
H. Gu
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Surface Oxidation ◽  
Force Balance ◽  
Contrast Imaging ◽  
Full Spectrum ◽  
High Temperature Mechanical Properties ◽  
Boundary Films ◽  
Z Contrast

High temperature mechanical properties of structural ceramics Si3N4 are controlled by ∼1 nm thick silicate amorphous films covering all grain boundaries. The composition of the film dictates the equilibrium film thickness resulted from a force balance at grain boundary. Many efforts arc brought to alter film chemistry and thickness, and this system offers ideal model materials to understand grain boundary and property relationship. Using a dedicated STEM (VG HB601) with high spatial resolution EELS analysis and high resolution Z-contrast imaging, various novel quantification data of the grain boundary in Si3N4 can be obtained. The methods described here can also be applied to other types of grain boundaries.EELS profiling was performed to acquire a full spectrum from each position at a lateral increment of 1Å across a boundary in a pure Si3N4 sample with only SiO2 impurities from surface oxidation. It gives directly elemental distributions near the boundary such as Si, N and O profiles shown in Fig. 1.

Microstructural Characterization of Rapidly Solidified Carbide-Containing Ni-Base Superalloys

1985 ◽  
Vol 43 ◽  
pp. 48-49
Author(s):  
E. L. Hall ◽  
M. R. Jackson
Keyword(s):  
Melt Spinning ◽  
Base Alloy ◽  
Eutectic Reaction ◽  
Microstructural Characterization ◽  
Weight Percent ◽  
Primary Carbide ◽  
Temperature Capability ◽  
Nickel Base ◽  
Rapidly Solidified

The temperature capability of nickel-base superalloys which are used in aircraft turbines may be able to be extended if novel microstructures can be produced in these materials by rapid solidification. The primary goal of these efforts is to achieve a fine dispersion of small precipitates which are stable at high temperature in the alloys. One class of alloys which seem particularly promising are the eutectic superalloys, which solidify via a eutectic reaction in which a γ- γ’ matrix containing MC carbides is formed. For this investigation, alloys which contained either Ta, Ti, or V as the primary carbide former were studied. In all cases, the base alloy consisted of Ni-4%Co-4%Cr-5.5%Al-2%Mo-3%W-1.5%Re-0.3%C in weight percent. The alloys additionally contained either 9% Ta, 5.5% Ti, or 4.5% V (subsequently referred to as alloys A, B, and C, respectively). The alloys were rapidly solidified by melt-spinning in vacuum.

Observation of grain boundary segregation in advanced ceramics using high-resolution imaging SIMS

1995 ◽  
Vol 53 ◽  
pp. 324-325
Author(s):  
R. Levi-Setti ◽  
K. K. Soni ◽  
J. M. Chabala ◽  
A. M. Thompson
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
High Spatial Resolution ◽  
Imaging Techniques ◽  
Boundary Segregation ◽  
Ion Microprobe ◽  
Broad Beam ◽  
Resolution Imaging ◽  
Boundary Chemistry

The significance of grain boundaries in controlling processing and properties of ceramics is widely acknowledged. Through the addition of suitable dopants to ceramics, their processability and properties can be improved. These dopants may segregate to grain boundaries, but the characterization of boundary chemistry is a challenging task. Studies of segregation phenomena require the application of high-lateralresolution techniques such as STEM/AEM or surface sensitive techniques such as AES, XPS. These techniques require rigorous sample preparation and have their limitations.The scanning ion microprobe is a powerful tool that has exhibited unprecedented potential in the characterization of grain boundaries in ceramics. When interfaced to a mass spectrometer (magnetic sector in our case), this instrument allows mapping of many trace elements at nanometer level in bulk specimens. The combination of excellent sensitivity and high spatial resolution enables direct imaging of grain boundary segregants. The results thus obtained are free from artifacts that typically complicate analysis with broad beam, non-imaging techniques.

Grain Boundary Transformations in Bi-Doped Copper

1991 ◽  
Vol 238 ◽  
Author(s):  
Elsie C. Urdaneta ◽  
David E. Luzzi ◽  
Charles J. McMahon
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Treatment Time ◽  
High Resolution Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron

ABSTRACTBismuth-induced grain boundary faceting in Cu-12 at ppm Bi polycrystals was studied using transmission electron microscopy (TEM). The population of faceted grain boundaries in samples aged at 600°C was observed to increase with heat treatment time from 15min to 24h; aging for 72h resulted in de-faceting, presumably due to loss of Bi from the specimen. The majority of completely faceted boundaries were found between grains with misorientation Σ=3. About 65% of the facets of these boundaries were found to lie parallel to crystal plane pairs of the type {111}1/{111]2- The significance of these findings in light of recent high resolution electron microscopy experiments is discussed.

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