Directional Solidification of Refractory Intermetallics: Single Crystals and Composites

MRS Proceedings ◽

10.1557/proc-322-353 ◽

1993 ◽

Vol 322 ◽

Author(s):

David P. Pope ◽

Dilip M. Shah ◽

William Romanow ◽

Mark Huntley

Keyword(s):

Aspect Ratio ◽

Optical Imaging ◽

Directional Solidification ◽

Single Crystals ◽

Intermetallic Compounds ◽

Floating Zone ◽

Growth Axis ◽

Advantages And Disadvantages

AbstractDirectional solidification of intermetallic compounds using the optical imaging floating zone technique is discussed. The advantages and disadvantages of the technique are described, and the systems to which this technique has been applied are listed. Finally, application of the technique to growing in situ Cr2Nb/Nb composites is described. It is shown that well aligned, fine microstructures can be obtained using the technique. The aspect ratio of the Cr2Nb platelets is 200:1, or better, and are a few microns thick. The Cr2Nb has a strong <220> texture along the growth axis but the Nb is nearly random.

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Axial Alignment of Short-Fiber Titanium Aluminide Composites by Directional Solidification

MRS Proceedings ◽

10.1557/proc-194-97 ◽

1990 ◽

Vol 194 ◽

Cited By ~ 1

Author(s):

S. L. Kampe ◽

G. H. Swope ◽

L. Christodoulou

Keyword(s):

Aspect Ratio ◽

Plastic Strain ◽

Directional Solidification ◽

Titanium Aluminide ◽

Base Material ◽

Short Fiber ◽

Floating Zone ◽

Microstructural Evaluation ◽

The Matrix

AbstractThe floating zone directional solidification technique has been applied to an XDTM short-fiber-reinforced titanium aluminide ingot in an effort to produce in situ alignment of the reinforcement. Microstructural evaluation reveals that a general alignment of the high aspect ratio (>100:1) fibers occurs under specific imposed solidification conditions. These metallographic observations are supported by 800 ° C mechanical data, which indicate higher axial and reduced transverse strengths relative to the unprocessed base material which contains a dispersion of randomly oriented fibers. The increased strengths are observed to be a consequence of an increase in the matrix hardening due to accommodation of plastic strain around the fiber reinforcement.

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Effect of HfC Addition on Mechanical Properties of Nb-5Mo-2W-18Si In-Situ Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.261-263.1439 ◽

2004 ◽

Vol 261-263 ◽

pp. 1439-1444 ◽

Cited By ~ 3

Author(s):

Sheng Wu Wang ◽

Hisatoshi Hirai ◽

Tatsuo Tabaru ◽

A. Kitahara ◽

Hideto Ueno

Keyword(s):

Mechanical Properties ◽

Directional Solidification ◽

Base Composition ◽

Zone Melting ◽

Shearing Stress ◽

Floating Zone ◽

In Situ Composites ◽

Arc Melting ◽

Microcrack Propagation

Nb base in-situ composites with the base composition of Nb-5Mo-2W-18Si were prepared by conventional arc-melting and induction heating floating zone melting followed by directional solidification. To investigate the effect of HfC addition, Nb was replaced with 0, 1 and 2 mol% HfC. The in-situ composites predominantly have an eutectic microstructure consisting of Nb solid solution (NbSS) and (Nb,Mo,W))5Si3 (5-3 silicide). The strength at 1470 K and 1670 K increases without fracture toughness decreasing, with increasing the HfC content. Directional solidification also improves the strength at the high temperature. The slip band under the shearing stress occurs in the NbSS during plastic deformation, which contributes to suppress microcrack propagation. It seems that HfC addition reinforces the bonding strength at grain boundary or NbSS/5-3 silicide interface.

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Directional solidification of Ni–Ni3Si eutectic in situ composites by electron beam floating zone melting

Physica B Condensed Matter ◽

10.1016/j.physb.2012.12.010 ◽

2013 ◽

Vol 412 ◽

pp. 70-73 ◽

Cited By ~ 10

Author(s):

Chunjuan Cui ◽

Jun Zhang ◽

Kun Wu ◽

Dening Zou ◽

Youping Ma ◽

...

Keyword(s):

Electron Beam ◽

Directional Solidification ◽

Zone Melting ◽

Floating Zone ◽

In Situ Composites

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Effects of Variable Microaccelerations on Distribution of Impurity Inhomogeneities in the InSb: Te Single Crystals Grown by the Floating Zone Melting on the \Foton\" Satellite"

10.2514/6.iac-04-j.3.03 ◽

2004 ◽

Keyword(s):

Single Crystals ◽

Zone Melting ◽

Floating Zone

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In-situ observation of eutectic growth during directional solidification of succinonitrile - (D)camphor- neopentyl glycol alloys under imposed velocity transients

Acta Materialia ◽

10.1016/j.actamat.2020.11.011 ◽

2021 ◽

Vol 203 ◽

pp. 116469

Author(s):

V.T. Witusiewicz ◽

U. Hecht ◽

J. Fernandez ◽

J. Rodriguez ◽

J.M. Ezquerro

Keyword(s):

Directional Solidification ◽

Eutectic Growth ◽

In Situ Observation ◽

Neopentyl Glycol

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Evolution of Pore Ordering during Anodizing of Aluminum Single Crystals: In Situ Small-Angle X-ray Scattering Study

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.1c01482 ◽

2021 ◽

Author(s):

Ilya V. Roslyakov ◽

Andrei P. Chumakov ◽

Andrei A. Eliseev ◽

Alexey P. Leontiev ◽

Oleg V. Konovalov ◽

...

Keyword(s):

Single Crystals ◽

Small Angle ◽

X Ray ◽

X Ray Scattering ◽

Scattering Study ◽

Ray Scattering

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Atmospheric Ice Particle Shape Estimates from Polarimetric Radar Measurements and In Situ Observations

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-17-0111.1 ◽

2017 ◽

Vol 34 (12) ◽

pp. 2569-2587 ◽

Cited By ~ 15

Author(s):

Sergey Y. Matrosov ◽

Carl G. Schmitt ◽

Maximilian Maahn ◽

Gijs de Boer

Keyword(s):

Aspect Ratio ◽

Particle Shape ◽

Characteristic Size ◽

In Situ Measurements ◽

Department Of Energy ◽

Depolarization Ratio ◽

Suggested Approach ◽

Aspect Ratios ◽

Radar Measurements

AbstractA remote sensing approach to retrieve the degree of nonsphericity of ice hydrometeors using scanning polarimetric Ka-band radar measurements from a U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program cloud radar operated in an alternate transmission–simultaneous reception mode is introduced. Nonsphericity is characterized by aspect ratios representing the ratios of particle minor-to-major dimensions. The approach is based on the use of a circular depolarization ratio (CDR) proxy reconstructed from differential reflectivity ZDR and copolar correlation coefficient ρhυ linear polarization measurements. Essentially combining information contained in ZDR and ρhυ, CDR-based retrievals of aspect ratios are fairly insensitive to hydrometeor orientation if measurements are performed at elevation angles of around 40°–50°. The suggested approach is applied to data collected using the third ARM Mobile Facility (AMF3), deployed to Oliktok Point, Alaska. Aspect ratio retrievals were also performed using ZDR measurements that are more strongly (compared to CDR) influenced by hydrometeor orientation. The results of radar-based retrievals are compared with in situ measurements from the tethered balloon system (TBS)-based video ice particle sampler and the ground-based multiangle snowflake camera. The observed ice hydrometeors were predominantly irregular-shaped ice crystals and aggregates, with aspect ratios varying between approximately 0.3 and 0.8. The retrievals assume that particle bulk density influencing (besides the particle shape) observed polarimetric variables can be deduced from the estimates of particle characteristic size. Uncertainties of CDR-based aspect ratio retrievals are estimated at about 0.1–0.15. Given these uncertainties, radar-based retrievals generally agreed with in situ measurements. The advantages of using the CDR proxy compared to the linear depolarization ratio are discussed.

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Rapid and simple prenatal diagnosis of common chromosome disorders: advantages and disadvantages of the molecular methods FISH and QF-PCR

Reproduction ◽

10.1530/rep.0.1260279 ◽

2003 ◽

pp. 279-297 ◽

Cited By ~ 80

Author(s):

MA Hulten ◽

S Dhanjal ◽

B Pertl

Keyword(s):

Prenatal Diagnosis ◽

Sex Chromosome ◽

Chromosome Analysis ◽

Maternal Serum ◽

Molecular Techniques ◽

Maternal Serum Screening ◽

Advantages And Disadvantages ◽

Microscopy Analysis ◽

Chromosome Disorder

Molecular techniques have been developed for prenatal diagnosis of the most common chromosome disorders (trisomies 21, 13, 18 and sex chromosome aneuploidies) where results are available within a day or two. This involves fluorescence in situ hybridization (FISH) and microscopy analysis of fetal cells or quantitative fluorescence polymerase chain reaction (QF-PCR) on fetal DNA. Guidance is provided on the technological pitfalls in setting up and running these methods. Both methods are reliable, and the risk for misdiagnosis is low, although slightly higher for FISH. FISH is also more labour intensive than QF-PCR, the latter lending itself more easily to automation. These tests have been used as a preamble to full chromosome analysis by microscopy. However, there is a trend to apply the tests as 'stand-alone' tests for women who are at relatively low risk of having a baby with a chromosome disorder, in particular that associated with advanced age or results of maternal serum screening programmes. These women comprise the majority of those currently offered prenatal diagnosis with respect to fetal chromosome disorders and if introduced on a larger scale, the use of FISH and QF-PCR would lead to substantial economical savings. The implication, on the other hand, is that around one in 500 to one in 1000 cases with a mentally and/or physically disabling chromosome disorder would remain undiagnosed.

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