Standard Specification for Titanium Alloy Bars for Near Surface Mounts in Civil Structures

The deformation behavior during tension of titanium GRADE 2 and steel 3723HR samples is investigated. The distribution of localized plasticity foci in the near-surface layers of samples of two materials is studied. A correlation between the stages on deformation curves and evolution patterns of spatial localized plasticity foci on titanium alloy GRADE 2 and steel 3723HR is established. It is established that a different type of deformation diagrams σ=f (ε)) during tension of metallic materials is manifested in the different distribution character of deformation fields at different stages of the deformation curve.

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Variable Aperture Method of Ultrasonic Annular Array for the Detection of Addictive Manufacturing Titanium Alloy

Journal of Sensors ◽

10.1155/2020/6622047 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Wenchao Li ◽

Junjie Chang ◽

Wentao Li ◽

Xiaoyun Long

Keyword(s):

Titanium Alloy ◽

Acoustic Field ◽

Linear Array ◽

High Energy ◽

Distribution Model ◽

Near Surface ◽

High Attenuation ◽

Annular Array ◽

Array Transducer ◽

Variable Aperture

The ultrasonic annular array transducer usually has a stronger focusing acoustic field than the linear array and matrix transducer with the same number of array elements, and is more suitable for the detection of large thickness and high attenuation components. However, due to the special arrangement of array elements, the focusing beam cannot be deflected and has a large near field, which limits its application in practical detection. The element parameters of annular array transducer are often designed and analyzed according to the 2-D acoustic field model of a linear array transducer. Therefore, the 3-D acoustic field distribution model of the annular array transducer is established, and the influence of the element parameters on its spatial acoustic field focusing characteristics is analyzed. The design criteria of the array element division mode and element size are proposed, which can avoid the generation of high-energy side lobe and grating lobe, and have good axial acoustic field. Then, the influence of excitation aperture on the energy and size of focal spot at different depths is discussed. The dynamic focusing method with variable aperture of annular array is established, and the C-scan detection experiment is carried out on the addictive manufacturing titanium alloy specimen. The detection results show that the variable aperture method has better central amplitude consistency and imaging accuracy for different depth defects, and has better near surface detection ability than the fixed aperture method.

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Structural-phase state of near-surface layers of VT6 titanium alloy after femtosecond laser treatment

Letters on Materials ◽

10.22226/2410-3535-2020-3-243-248 ◽

2020 ◽

Vol 10 (3) ◽

pp. 243-248

Author(s):

Mikhail Zhidkov ◽

Nikita Smirnov ◽

Jiajun Chen ◽

Sergey Kudryashov ◽

Maksim Yapryntsev

Keyword(s):

Titanium Alloy ◽

Femtosecond Laser ◽

Laser Treatment ◽

Phase State ◽

Structural Phase ◽

Surface Layers ◽

Near Surface ◽

Structural Phase State

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Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

Journal of Paleontology ◽

10.1017/s0022336000058819 ◽

1988 ◽

Vol 62 (01) ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Ronald E. Martin

Keyword(s):

Deep Water ◽

Benthic Foraminifera ◽

Carbonate Platform ◽

Sedimentary Facies ◽

Depositional Environments ◽

Near Surface ◽

Sediment Gravity Flows ◽

Gravity Flows ◽

Platform Margin ◽

Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

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Analysis of 2D and 3D defects associated with precipitation of Cu in silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010008866x ◽

1991 ◽

Vol 49 ◽

pp. 870-871

Author(s):

P.M. Rice ◽

MJ. Kim ◽

R.W. Carpenter

Keyword(s):

Colony Growth ◽

Dark Field ◽

Dark Side ◽

Silicide Phase ◽

Strain Fields ◽

Near Surface ◽

Unknown Composition ◽

Secondary Precipitates ◽

20 Nm ◽

2D And 3D

Extrinsic gettering of Cu on near-surface dislocations in Si has been the topic of recent investigation. It was shown that the Cu precipitated hetergeneously on dislocations as Cu silicide along with voids, and also with a secondary planar precipitate of unknown composition. Here we report the results of investigations of the sense of the strain fields about the large (~100 nm) silicide precipitates, and further analysis of the small (~10-20 nm) planar precipitates.Numerous dark field images were analyzed in accordance with Ashby and Brown's criteria for determining the sense of the strain fields about precipitates. While the situation is complicated by the presence of dislocations and secondary precipitates, micrographs like those shown in Fig. 1(a) and 1(b) tend to show anomalously wide strain fields with the dark side on the side of negative g, indicating the strain fields about the silicide precipitates are vacancy in nature. This is in conflict with information reported on the η'' phase (the Cu silicide phase presumed to precipitate within the bulk) whose interstitial strain field is considered responsible for the interstitial Si atoms which cause the bounding dislocation to expand during star colony growth.

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Shock consolidation of Ni-Ti alloy powder

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143730 ◽

1986 ◽

Vol 44 ◽

pp. 430-431

Author(s):

Naresh N. Thadhani ◽

Thad Vreeland ◽

Thomas J. Ahrens

Keyword(s):

Alloy Powder ◽

Amorphous Material ◽

Ti Alloy ◽

Two Phase ◽

Near Surface ◽

Optical Micrograph ◽

Shock Compaction ◽

Powder Particles ◽

Ti Powder ◽

Rapidly Solidified

A spherically-shaped, microcrystalline Ni-Ti alloy powder having fairly nonhomogeneous particle size distribution and chemical composition was consolidated with shock input energy of 316 kJ/kg. In the process of consolidation, shock energy is preferentially input at particle surfaces, resulting in melting of near-surface material and interparticle welding. The Ni-Ti powder particles were 2-60 μm in diameter (Fig. 1). About 30-40% of the powder particles were Ni-65wt% and balance were Ni-45wt%Ti (estimated by EMPA).Upon shock compaction, the two phase Ni-Ti powder particles were bonded together by the interparticle melt which rapidly solidified, usually to amorphous material. Fig. 2 is an optical micrograph (in plane of shock) of the consolidated Ni-Ti alloy powder, showing the particles with different etching contrast.

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Preparation of cross-sectional samples for near-surface TEM studies

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012669x ◽

1987 ◽

Vol 45 ◽

pp. 380-381

Author(s):

R.C. Dickenson ◽

K.R. Lawless

Keyword(s):

Standard Sample ◽

Surface Region ◽

Specimen Preparation ◽

Thick Sheet ◽

Drill Bit ◽

Sample Holder ◽

Metal Interface ◽

Cross Sectional ◽

Near Surface ◽

Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

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Near-Surface Aggregation of Sn In Heavily Sn-Doped GaAs Films Grown By Molecular Beam Epitaxy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118710 ◽

1985 ◽

Vol 43 ◽

pp. 368-369

Author(s):

S. H. Chen

Keyword(s):

Molecular Beam Epitaxy ◽

Cross Section ◽

Electron Spectroscopy ◽

Molecular Beam ◽

Surface Segregation ◽

Secondary Ion Mass Spectrometry ◽

Specimen Preparation ◽

Near Surface ◽

Gaas Films ◽

Secondary Ion

Sn has been used extensively as an n-type dopant in GaAs grown by molecular-beam epitaxy (MBE). The surface accumulation of Sn during the growth of Sn-doped GaAs has been observed by several investigators. It is still not clear whether the accumulation of Sn is a kinetically hindered process, as proposed first by Wood and Joyce, or surface segregation due to thermodynamic factors. The proposed donor-incorporation mechanisms were based on experimental results from such techniques as secondary ion mass spectrometry, Auger electron spectroscopy, and C-V measurements. In the present study, electron microscopy was used in combination with cross-section specimen preparation. The information on the morphology and microstructure of the surface accumulation can be obtained in a fine scale and may confirm several suggestions from indirect experimental evidence in the previous studies.

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