In Situ Composites Prepared By Solidification And Mechanical Techniques

1981 ◽  
Vol 12 ◽  
Author(s):  
J. D. Verhoeven
Keyword(s):  
Phase 1 ◽  
Copper Alloys ◽  
High Strength ◽  
Wire Drawing ◽  
Two Phase ◽  
Random Array ◽  
Wide Range ◽  
Dendritic Phase ◽  
Size And Morphology

ABSTRACTAn alternate in situ technique is presented for preparation of aligned microstructures which has been successfully applied to the preparation of copper alloys. In this technique, a two phase alloy is first prepared by conventional casting techniques to produce a random array of dendrites of phase 1 in a matrix of phase 2. The casting is then reduced to wire size by mechanical reductions. It is demonstrated that the alignment of the dendritic phase produced by the mechanical reduction is surprisingly good, and that one can achieve a wide range of microstructural control over the filament size and morphology by utilization of controlled coarsening anneals followed by additional wire drawing. Examples are presented of Cu-Nb alloys which are converted to Nb3 Sn-Cu superconducting wires possessing excellent critical current values, and of Fe-Cu alloys which produce wires having quite high strength to resistivity ratios.

Ultra Fast In Situ X-Ray Micro-Tomography: Application to Solidification of Aluminium Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 1713-1718 ◽  
Author(s):  
Luc Salvo ◽  
Marco Di Michiel ◽  
Mario Scheel ◽  
Pierre Lhuissier ◽  
B. Mireux ◽  
...  
Keyword(s):  
Solid Phase ◽  
Early Stage ◽  
Copper Alloys ◽  
Cmos Technology ◽  
Acquisition Time ◽  
X Ray ◽  
Research Fields ◽  
Wide Range ◽  
Micro Tomography

X-ray micro-tomography has been applied recently in a wide range of research fields (damage in materials, solidification …). Thanks to the high flux of synchrotrons and specific cameras the total time to acquire a scan was considerably reduced. The use of a specific camera based on CMOS technology allows dividing the acquisition time for a complete scan by a factor of 100. Therefore we have been able to perform in situ solidification of aluminium-copper alloys at high cooling rates (between 1 and 10°C/s) and we will show results concerning the evolution of the microstructure in 3D in the early stage of solidification, in particular the morphology of the solid phase and the kinetics of growth.

scholarly journals Enhancing Label Representations with Relational Inductive Bias Constraint for Fine-Grained Entity Typing

2021 ◽  
Author(s):  
Jinqing Li ◽  
Xiaojun Chen ◽  
Dakui Wang ◽  
Yuwei Li
Keyword(s):  
State Of The Art ◽  
Phase 1 ◽  
Phase 2 ◽  
Two Phase ◽  
Inductive Bias ◽  
Fine Grained ◽  
Wide Range ◽  
Dynamic Experiments ◽  
Novel Method ◽  
Public Datasets

Fine-Grained Entity Typing (FGET) is a task that aims at classifying an entity mention into a wide range of entity label types. Recent researches improve the task performance by imposing the label-relational inductive bias based on the hierarchy of labels or label co-occurrence graph. However, they usually overlook explicit interactions between instances and labels which may limit the capability of label representations. Therefore, we propose a novel method based on a two-phase graph network for the FGET task to enhance the label representations, via imposing the relational inductive biases of instance-to-label and label-to-label. In the phase 1, instance features will be introduced into label representations to make the label representations more representative. In the phase 2, interactions of labels will capture dependency relationships among them thus make label representations more smooth. During prediction, we introduce a pseudo-label generator for the construction of the two-phase graph. The input instances differ from batch to batch so that the label representations are dynamic. Experiments on three public datasets verify the effectiveness and stability of our proposed method and achieve state-of-the-art results on their testing sets.

scholarly journals Preparation, Characterization, and Optimization of an In Vitro C30 Carotenoid Pathway

2005 ◽  
Vol 71 (11) ◽  
pp. 6578-6583 ◽  
Author(s):  
Bosung Ku ◽  
Jae-Cheol Jeong ◽  
Benjamin N. Mijts ◽  
Claudia Schmidt-Dannert ◽  
Jonathan S. Dordick
Keyword(s):  
Phase System ◽  
Reaction Conditions ◽  
Two Phase ◽  
Gene Encoding ◽  
In Situ Extraction ◽  
Steady State Kinetics ◽  
Wide Range ◽  
Carotenoid Synthesis

ABSTRACT The ispA gene encoding farnesyl pyrophosphate (FPP) synthase from Escherichia coli and the crtM gene encoding 4,4′-diapophytoene (DAP) synthase from Staphylococcus aureus were overexpressed and purified for use in vitro. Steady-state kinetics for FPP synthase and DAP synthase, individually and in sequence, were determined under optimized reaction conditions. For the two-step reaction, the DAP product was unstable in aqueous buffer; however, in situ extraction using an aqueous-organic two-phase system resulted in a 100% conversion of isopentenyl pyrophosphate and dimethylallyl pyrophosphate into DAP. This aqueous-organic two-phase system is the first demonstration of an in vitro carotenoid synthesis pathway performed with in situ extraction, which enables quantitative conversions. This approach, if extended to a wide range of isoprenoid-based pathways, could lead to the synthesis of novel carotenoids and their derivatives.

scholarly journals Strengthening Mechanisms in Nickel-Copper Alloys: A Review

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1358
Author(s):  
Olexandra Marenych ◽  
Andrii Kostryzhev
Keyword(s):  
Heat Treatment ◽  
Copper Alloys ◽  
High Strength ◽  
Wire Drawing ◽  
Strengthening Mechanisms ◽  
Processing Technologies ◽  
Cu Alloys ◽  
Excellent Corrosion Resistance ◽  
Nickel Copper ◽  
Marine Vessels

Nickel-Copper (Ni-Cu) alloys exhibit simultaneously high strength and toughness, excellent corrosion resistance, and may show good wear resistance. Therefore, they are widely used in the chemical, oil, and marine industries for manufacturing of various components of equipment, such as: drill collars, pumps, valves, impellers, fixtures, pipes, and, particularly, propeller shafts of marine vessels. Processing technology includes bar forging, plate and tube rolling, wire drawing followed by heat treatment (for certain alloy compositions). Growing demand for properties improvement at a reduced cost initiate developments of new alloy chemistries and processing technologies, which require a revision of the microstructure-properties relationship. This work is dedicate to analysis of publicly available data for the microstructure, mechanical properties and strengthening mechanisms in Ni-Cu alloys. The effects of composition (Ti, Al, Mn, Cr, Mo, Co contents) and heat treatment on grain refinement, solid solution, precipitation strengthening, and work hardening are discussed.

Preparation of in Situ Cu-Nb Composite Sheet and Wire for Tem Analysis

1987 ◽  
Vol 115 ◽  
Author(s):  
C. L. Trybus ◽  
F. C. Laabs ◽  
A. R. Pelton ◽  
V. A. Spitzig
Keyword(s):  
Electrochemical Techniques ◽  
Wire Drawing ◽  
Thick Sheet ◽  
Two Phase ◽  
Tem Analysis ◽  
Excessive Heat ◽  
Transmission Electron ◽  
Transmission Electron Microscopy Characterization ◽  
Microscopy Characterization

ABSTRACTCu-Nb in situ composites attain anomolous increases in strength upon mechanical deformation. The unique filamentary microstructures that evolve during processing (cold rolling and/or wire drawing) are the source of the strengthening. Results from transmission electron microscopy characterization studies have played a key role in the understanding of the relationships between structure and properties. However, the fabrication of reliable TEM samples has been extremely challenging for the following reasons: (1) traditional electrochemical techniques are not suitable for the two-phase microstructure, (2) preparation of longitudinal and transverse sections of fine (∼150 μm diameter wires) and thin (∼60 μm thick) sheet is tedious, and (3) it is necessary to avoid excessive heat (< 30°C) during sample preparation to preserve the metastable structural arrangements. This paper will review the procedures used to prepare TEM specimens from bulk wire and sheet samples as well as from extracted Nb filaments. Proper techniques for plating, mounting, sectioning, polishing, and ion-thinning will be discussed.

The Modeling of Flow Concentration in Two-Phase Materials

1976 ◽  
Vol 98 (2) ◽  
pp. 180-189 ◽  
Author(s):  
T. S. Cook ◽  
C. A. Rau ◽  
E. Smith
Keyword(s):  
Development Program ◽  
High Strength ◽  
Theoretical Models ◽  
Operating Conditions ◽  
Micromechanical Modeling ◽  
High Yield ◽  
Experimental Investigations ◽  
Two Phase ◽  
Wide Range ◽  
Materials Research

Many high strength alloys that are developed for arduous operating conditions have essentially a two-phase microstructure that is produced by a precipitation-hardening procedure. However, alloys that are heat-treated to have maximum hardness, often have poor monotonic and poor fatigue fracture characteristics when these are assessed in relation to their high yield strengths, and this imposes limits to their use for service applications. Experimental investigations covering a wide range of precipitation-hardened alloys have shown that the inferior fracture properties are due to plastic deformation being concentrated within narrow zones. Against this background, Pratt & Whitney Aircraft is undertaking a comprehensive theoretical investigation based on the representation of flow concentration by appropriate theoretical models. The general objective is to provide a quantitative understanding of flow concentration, both with respect to its causes and consequences, in terms of both material and externally imposed parameters such as, for example, the state of loading. The aim of the present paper is not to survey the complete problem of flow concentration in the light of the research undertaken to date, but to provide a limited number of examples that illustrate how specific aspects of the problem have been considered using appropriate models to describe the operative physical processes. With the Conference’s objectives in mind, the paper’s general intention is therefore to provide further evidence that micromechanical modeling can be successfully used to relate mechanical behavior with metallurgical parameters, and thereby add further support for the view that such work forms an integral part of any balanced materials research and development program.

scholarly journals Influence of steel cleanliness on drawability of fine filaments with high tensile strength

2019 ◽  
Vol 116 (5) ◽  
pp. 513
Author(s):  
Julie Godon ◽  
Pascal Antoine ◽  
Jean Bernard Vogt ◽  
Jérémie Bouquerel
Keyword(s):  
Chemical Composition ◽  
Critical Size ◽  
High Strength ◽  
Wire Drawing ◽  
High Carbon ◽  
Total Oxygen ◽  
Total Oxygen Content ◽  
Wide Range ◽  
The Matrix ◽  
Steel Cleanliness

The aim of the current study is to clarify the influence of steel cleanliness on the fracture during wet wire drawing of high strength high carbon very fine filaments. Methodologies for inclusion identification and for inclusion count were developed. Ninety percent of the fractured filaments were associated with an inclusion which was SiO2, or SiO2-CaO or SiO2-MgO. The fracture of the wires resulted from debonding of the inclusion from the matrix. Inclusion density assessed from total oxygen content in the wire was successfully and reliably obtained. Inclusions exhibited a wide range of sizes but mostly around 6 μm. The inclusion density did not appear as the only parameter that affects the fracture occurrence. An important effect of size and of chemical composition of the inclusions was found. A critical size of inclusions for fracture was observed but it depends on the chemical composition of inclusions.

Design of Pre-Acidification Reactors for the Anaerobic Treatment of Industrial Wastewaters

1994 ◽  
Vol 29 (9) ◽  
pp. 199-204 ◽  
Author(s):  
I. E. Alexiou ◽  
G. K. Anderson ◽  
L. M. Evison
Keyword(s):  
Industrial Wastewater ◽  
Volatile Fatty Acids ◽  
High Strength ◽  
Pilot Scale ◽  
Anaerobic Treatment ◽  
Coffee Production ◽  
Two Phase ◽  
Industrial Wastewaters ◽  
Wide Range ◽  
Pre Treatment

Two-phase anaerobic digestion has often been considered beneficial for the treatment of high strength industrial wastewaters, especially when the first phase is used as a pre-treatment system known as pre-acidification. Several applications in the field of industrial wastewater treatment have been reviewed in order to evaluate the advantages of the pre-acidification process and its effects on the methanogenic reactor. Although pre-acidification has obvious advantages, complete acidification may be detrimental to the efficiency of the overall process. The use of balancing tanks at full-scale has been common practice for the pre-acidification of a wide range of wastewaters yet no accepted design criteria for acidogenic reactors have been formulated and two-phase applications are generally based upon previous experience. The paper summarizes the results of a two year investigation into pre-acidification at both bench- and pilot-scale, presents the results of instant coffee production wastewaters and discusses a wide range of parameters which have been evaluated. Operating criteria will be discussed and guidelines for the design of pre-acidification reactors will be presented. Finally alternatives to using the total VFA (volatile fatty acids) concentrations for expressing the efficiency of acidogenesis will be introduced.

scholarly journals Ultrafine-Grained High Strength Cu-Ni-Si Alloys

2017 ◽  
Vol 892 ◽  
pp. 64-69 ◽  
Author(s):  
Igor Altenberger ◽  
Hans Achim Kuhn ◽  
Mozhgan Gholami-Kermanshahi ◽  
Mansour Mhaede ◽  
Manfred Wollmann ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Copper Alloys ◽  
Pure Copper ◽  
High Strength ◽  
Solid Solution Hardening ◽  
Subsequent Aging ◽  
Ultrafine Grained ◽  
Wide Range

Ultrafine-grained (UFG) pure copper has been in the focus of materials scientists over the last two decades, however ultrafine-grained high-strength copper alloys have scarcely been processed or characterized so far industrially.In this contribution, UFG copper alloys, especially Cu-Ni-Si alloys, being well known as ideal materials for electromechanical connectors, springs and leadframes, are presented. Precipitation hardened Cu-Ni-Si alloys are a well established and technologically important class of materials for a wide range of applications where high strength and good conductivity are required. Yield strength and fatigue properties of metallic alloys can be significantly enhanced by severe plastic deformation methods. In contrast to other strengthening methods such as solid solution hardening, severe plastic deformation leads to a weaker decrease of electrical conductivity and is therefore a means of enhancing strength while maintaining acceptable conductivity for current bearing parts and components. Characterization of these materials after severe plastic deformation by swaging, wire drawing and subsequent aging was carried out using conductivity-, hardness-and tensile tests as well as highly-resolved microstructural characterization methods.The results reveal that UFG low alloyed copper alloys exhibit impressive combinations of properties such as strength, conductivity, high ductility as well as acceptable thermal stability at low and medium temperatures. By a subsequent aging treatment the severely plastically deformed microstructure of Cu-Ni-Si alloys can be further enhanced and thermal stability can profit from grain-boundary pinning by precipitated nanoscale nickel silicides.

Ductile Dendritic Phase Reinforced Ti-Base Bulk Metallic Glass-Forming Alloys

2002 ◽  
Vol 754 ◽  
Author(s):  
G. He ◽  
J. Eckert ◽  
W. Löser ◽  
L. Schultz
Keyword(s):  
Shear Banding ◽  
Shear Bands ◽  
High Strength ◽  
Deformation Mode ◽  
Inhomogeneous Deformation ◽  
Matrix Composites ◽  
Glass Forming ◽  
Show Evidence ◽  
Dendritic Phase

ABSTRACTBulk metallic glasses (BMG) exhibit high strength but limited ductility due to their inhomogeneous deformation behavior under load, which seriously limits their application. To prevent the inhomogeneous deformation, attempts have been made by introducing in situ formed ductile dendritic phases in present study. Ti-base BMG-forming alloys were selected and modified by adding refractory metals Nb, Ta, Mo and Zr. Ductile dendrites / nanostructured matrix composites were synthesized which exhibit a plastic strain larger than 14% together with high strength (ultimate strength higher than 2400 MPa). The experimental results show evidence that shear banding is the main deformation mode in nanostructured matrix. The localized shear bands are limited in the inter-dendrite regions by micrometer-sized dendrites. The dendrites act as obstacles to limit the excessive deformation in the localized shear bands and contribute to the plasticity by dislocations.

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