Investigation of Al–Pb nanocomposites synthesized by nonequilibrium processes

1998 ◽  
Vol 13 (2) ◽  
pp. 308-315 ◽  
Author(s):  
H. W. Sheng ◽  
F. Zhou ◽  
Z. Q .Hu ◽  
K. Lu
Keyword(s):  
Melt Spinning ◽  
Milling Time ◽  
Nanometer Scale ◽  
Maximum Hardness ◽  
Nonequilibrium Processes ◽  
Minimum Particle Size ◽  
Melt Spun ◽  
The Matrix ◽  
Orientational Relationship ◽  
Al Matrix

Two nonequilibrium processes (melt-spinning and ball-milling) were successfully employed to synthesize Al1−xPbx (x = 5, 10, 20, 30 wt. %) nanocomposites with distinct microstructures. In the melt-spun (MS) Al–Pb alloys, the nanometer-sized Pb particles are uniformly distributed in the micrometer-grained Al matrix and have an orientational relationship with the matrix, while in the ball-milled (BM) samples, both Pb and Al components are refined with prolonged milling time, forming nanocomposites with Pb particles homogeneously dispersed into the Al matrix. The minimum particle size of Pb in the milled samples linearly increases with the Pb content. The microhardness of the BM Al–Pb samples is much larger than that of the MS samples, which mainly results from strengthening effects of the nanometer scale Al grains following the Hall–Petch relationship. The microhardness for both BM and MS Al–Pb samples varies with the Pb content, and maximum hardness for both samples exists when Pb content is about 5 wt. %, indicating that small amounts of Pb, in the form of nanoparticles, may strengthen the Al matrix.

HRTEM Study of Nanostructures in Hydrogen-Absorbing Mg-Ni and Mg-Ni-La Alloys Prepared by Melt-Spinning

2007 ◽  
Vol 561-565 ◽  
pp. 1629-1632 ◽  
Author(s):  
K. Tanaka ◽  
T. Miwa ◽  
K. Morishita ◽  
Katsuhiro Sasaki ◽  
Kotaro Kuroda
Keyword(s):  
Nanostructured Materials ◽  
Melt Spinning ◽  
Hydrogen Transport ◽  
Melt Spun ◽  
The Matrix ◽  
Nano Grains

The structure of melt-spun and crystallized Mg-10%Ni and Mg-10%Ni-5%La alloys is studied using HRTEM, coupled with ED and EELS techniques, for specimens subjected to hydrogenation and dehydrogenation. The presence of nano-sized (5-10nm) Mg2Ni grains dispersed in the matrix of Mg nano-grains is observed before hydrogenation. This structure is almost preserved after hydrogenation and dehydrogenation at 300°C. In the hydrogenated specimen, nanoboundaries lying between MgH2 and Mg2NiH4 nano-grains are observed. They appear to provide main routes for the hydrogen transport in these nanostructured materials.

Epitaxial dependence of the melting behavior of In nanoparticles embedded in Al matrices

1997 ◽  
Vol 12 (1) ◽  
pp. 119-123 ◽  
Author(s):  
H. W. Sheng ◽  
G. Ren ◽  
L. M. Peng ◽  
Z. Q. Hu ◽  
K. Lu
Keyword(s):  
Differential Scanning Calorimetry ◽  
Melting Point ◽  
Melting Temperature ◽  
Melt Spinning ◽  
Melting Behavior ◽  
Scanning Calorimetry ◽  
Equilibrium Melting Point ◽  
Milled Sample ◽  
Melt Spun ◽  
Al Matrix

Nanometer-sized In particles (5−45 nm) embedded in the Al matrix were prepared by using melt-spinning and ball-milling techniques. Different crystallographic orientationships between In nanoparticles and the Al matrix were constructed by these two approaches. Melting behavior of the In particles were investigated by means of differential scanning calorimetry (DSC). It was found that the epitaxially oriented In nanoparticles (with the Al matrix) in the melt-spun sample were superheated to about 0−38 °C, whereas the randomly oriented In particles in the ball-milled sample melted below its equilibrium melting point by about 0−22 °C. We suggest that the melting temperature of In nanoparticles can be either enhanced or depressed, depending on the epitaxy between In and the Al matrix.

Processing and Microstructure of Melt Spun Niai Alloys

1988 ◽  
Vol 133 ◽  
Author(s):  
I. E. Locci ◽  
R. D. Noebe ◽  
J. A. Moser ◽  
D. S. Lee ◽  
M. Nathal
Keyword(s):  
Melt Spinning ◽  
Matrix Material ◽  
Fiber Reinforced Composites ◽  
Ribbon Thickness ◽  
Reinforced Composites ◽  
Continuous Fiber ◽  
Grain Sizes ◽  
Melt Spun ◽  
The Matrix ◽  
Microscopy Techniques

ABSTRACTThe influence of various melt spinning parameters and the effect of consolidation on the microstructure of melt spun NiAl and NiAl + W alloys have been examined by optical and electron microscopy techniques. It was found that the addition of 0.5 at.% W to NiAl results in a fine dispersion of W particles after melt spinning which effectively controls grain growth during annealing treatments or consolidation at temperatures between 1523 and 1723 K. Increased wheel speeds are effective at reducing both ribbon thickness and grain size, such that proper choice of both composition and casting parameters can produce structures with grain sizes as small as 2 μ m. Finally, fabrication of continuous fiber reinforced composites which used pulverized ribbon as the matrix material was demonstrated.

Microstructure of Rapidly Solidified Al-Si Exhibiting Enhanced Superconducting Properties

1985 ◽  
Vol 62 ◽  
Author(s):  
M. A. Noack ◽  
A. J. Drehman ◽  
A. R. Pelton
Keyword(s):  
Melt Spinning ◽  
Thick Layer ◽  
Bottom Surface ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Fine Grained ◽  
Melt Spun ◽  
The Matrix ◽  
Rapidly Solidified ◽  
Insight Into

ABSTRACTTsuei and Johnson previously reported significantly enhanced superconducting transition temperatures for rapidly solidified Al-Si alloys. Here we report a microstructural study of melt spun Al80 Si20 ribbons to determine the mechanism responsible for this enhancement.Results of this investigation revealed three distinct microstructures from the top surface to the more rapidly cooled bottom surface (which was in contact with the melt-spinning wheel). Near the top, the microstructure is of hypoeutectic morphology even though this is a hypereutectic alloy. The predominant microstructure is cellular. A 1 to 3 Wm thick layer at the bottom of the ribbon was found to be responsible for the largest enhancement. This layer is composed of fine-grained supersaturated fcc Al containing densely distributed dc Si precipitates. Microdiffraction analysis revealed a cube/cube orientation relationship between the precipitates and the matrix. These results provide insight into the possible mechanism for the enhancement.

scholarly journals Effect of Cooling Rate on the Microstructure Evolution and Mechanical Properties of Iron-Rich Al–Si Alloy

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 411
Author(s):  
Xiao Shen ◽  
Shuiqing Liu ◽  
Xin Wang ◽  
Chunxiang Cui ◽  
Pan Gong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Cooling Rate ◽  
Melt Spinning ◽  
Silicon Phase ◽  
Rich Phase ◽  
The Matrix ◽  
Granular Morphology ◽  
Morphology Changes ◽  
Al Matrix

The mechanical properties of iron-rich Al–Si alloy is limited by the existence of plenty of the iron-rich phase (β-Al5FeSi), whose unfavorable morphology not only splits the matrix but also causes both stress concentration and interface mismatch with the Al matrix. The effect of the cooling rate on the tensile properties of Fe-rich Al–Si alloy was studied by the melt spinning method at different rotating speeds. At the traditional casting cooling rate of ~10 K/s, the size of the needle-like β-Al5FeSi phase is about 80 μm. In contrast, the size of the β-Al5FeSi phase is reduced to 500 nm and the morphology changes to a granular morphology with the high cooling rate of ~104 K/s. With the increase of the cooling rate, the morphology of the β-Al5FeSi phase is optimized, meanwhile the tensile properties of Fe-rich Al–Si alloy are greatly improved. The improved tensile properties of the Fe-rich Al-Si alloy is attributed to the combination of Fe-rich reinforced particles and the granular silicon phase provided by the high cooling rate of the melt spinning method.

MICROSTRUCTURE AND THERMOELECTRIC PROPERTIES OF (Zr,Hf)NiSn-BASED HALF-HEUSLER ALLOYS BY MELT SPINNING AND SPARK PLASMA SINTERING

2010 ◽  
Vol 03 (04) ◽  
pp. 227-231 ◽  
Author(s):  
CUI YU ◽  
TIEJUN ZHU ◽  
KAI XIAO ◽  
JUNJIE SHEN ◽  
XINBING ZHAO
Keyword(s):  
Thermal Conductivity ◽  
Spark Plasma Sintering ◽  
Melt Spinning ◽  
Lattice Thermal Conductivity ◽  
Heusler Alloys ◽  
Grain Sizes ◽  
Plasma Sintering ◽  
Melt Spun ◽  
The Matrix ◽  
Spark Plasma

(Zr,Hf)NiSn -based half-Heusler thermoelectric materials have been prepared by melt spinning and spark plasma sintering to refine the grain size. The grain sizes of the melt-spun thin ribbons varied from ~500 nm to ~3 μm and no significant grain growth were found for the bulk samples compacted by spark plasma sintering. Nanoscale precipitates dispersed in the matrix were observed, which should be more metallic due to the increase of the electrical conductivity. The reduction of lattice thermal conductivity was observed due to the refined grain sizes.

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.

Experimental Investigation and Micro-Structural Evolution Analysis of CNT & Fly Ash Reinforced Aluminium Matrix Composites

2015 ◽  
Vol 830-831 ◽  
pp. 429-432 ◽  
Author(s):  
Udaya ◽  
Peter Fernandes
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Fly Ash ◽  
Ball Milling ◽  
Milling Time ◽  
Structural Evolution ◽  
Matrix Composites ◽  
Evolution Analysis ◽  
Ball Milling Time ◽  
Al Matrix

The paper illustrates Carbon nanotubes reinforced pure Al (CNT/Al) composites and fly ash reinforced pure Al (FA/Al) composites produced by ball-milling and sintering. Microstructures of the fabricated composite were examined and the mechanical properties of the composites were tested and analysed. It was indicated that the CNTs and fly ash were uniformly dispersed into the Al matrix as ball-milling time increased with increase in hardness.

scholarly journals Thermal and Mechanical Behavior of Elastomers Incorporated with Thermoregulating Microcapsules

2021 ◽  
Vol 11 (12) ◽  
pp. 5370
Author(s):  
Ana M. Borreguero ◽  
Irene Izarra ◽  
Ignacio Garrido ◽  
Patrycja J. Trzebiatowska ◽  
Janusz Datta ◽  
...  
Keyword(s):  
Latent Heat ◽  
Continuous Improvement ◽  
Low Density Polyethylene ◽  
Molar Ratio ◽  
Low Density ◽  
Minimum Particle Size ◽  
Synergy Effects ◽  
Elastomeric Materials ◽  
The Matrix ◽  
Spherical Microparticles

Polyurethane (PU) is one of the principal polymers in the global plastic market thanks to its versatility and continuous improvement. In this work, PU elastomeric materials having thermoregulating properties through the incorporation of microcapsules (mSD-(LDPE·EVA-RT27)) from low-density polyethylene and vinyl acetate containing paraffin®RT27 as PCM were produced. Elastomers were synthesized while varying the molar ratio [NCO]/[OH] between 1.05 and 1.1 and the microcapsule (MC) content from 0.0 to 20.0 wt.%. The successful synthesis of the PUs was confirmed by IR analyses. All the synthesized elastomers presented a structure formed by a net of spherical microparticles and with a minimum particle size for those with 10 wt.% MC. The density and tensile strength decreased with the MC content, probably due to worse distribution into the matrix. Elastomer E-1.05 exhibited better structural and stability properties for MC contents up to 15 wt.%, whereas E-1.1, containing 20 wt.% MC, revealed mechanical and thermal synergy effects, demonstrating good structural stability and the largest latent heat. Hence, elastomers having a large latent heat (8.7 J/g) can be produced by using a molar ratio [NCO]/[OH] of 1.1 and containing 20 wt.% mSD-(LDPE·EVA-RT27).

Microstructural Studies of NiCoMnIn Magnetic Shape Memory Ribbons

2013 ◽  
Vol 738-739 ◽  
pp. 436-440 ◽  
Author(s):  
Krystian Prusik ◽  
Katarzyna Bałdys ◽  
Danuta Stróż ◽  
Tomasz Goryczka ◽  
Józef Lelątko
Keyword(s):  
Melt Spinning ◽  
Room Temperature ◽  
Parent Phase ◽  
Magnetic Shape Memory ◽  
Melt Spun ◽  
Columnar Grains ◽  
Ebsd Technique ◽  
Microstructural Studies ◽  
Melt Spinning Technique ◽  
Scanning Electron

In present paper two ribbons of the Ni44Co6Mn36In14 (at.%) were prepared under different melt-spinning technique conditions. Microstructure of the ribbons was studied by scanning electron microscopy (SEM). Depending on the liquid ejection overpressure two types of ribbons microstructures were observed. Ribbon T1 for which ejection overpressure was 1.5 bar showed typical melt-spun ribbon microstructure consisting of a top layer of small equi-axial grains and columnar grains below. For T2 ribbon (ejection overpressure 0.2 bar) only a small fraction of the columnar grains were observed. Structure analysis of the ribbons performed by XRD showed that at room temperature both ribbons have B2 parent phase superstructure. No gamma phase precipitates were observed. In order to determine the orientation of the grains the EBSD technique was applied.

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