scholarly journals The Early Stages of the Microstructural Development of the Colony Structure in Bi-2223 Tapes

2001 ◽  
Vol 689 ◽  
Author(s):  
T. G. Holesinger
Keyword(s):  
Liquid Phase ◽  
Texture Evolution ◽  
Secondary Phase ◽  
Primary Phase ◽  
Microstructural Development ◽  
Colony Structure ◽  
Secondary Phases ◽  
Phase Development ◽  
Multifilamentary Tapes

ABSTRACTThe current protocol for processing (Bi,Pb)2Sr2Ca2Cu3O10-x (Bi-2223) multifilamentary tapes involves the in situ formation of the primary phase from a suitable mixture of precursor phases. As such, the developments during the first few minutes of heat treatment determine to a large extent the efficiency of primary phase development, competing secondary phase development, texture evolution, and grain-to-grain connectivity. This work documents the development of the liquid phase, secondary phases, defects which may affect alignment and reaction kinetics, and the precipitation of Bi-2223 from the liquid phase.

scholarly journals Influence of Fe and Mn on the Microstructure Formation in 5xxx Alloys—Part I: Evolution of Primary and Secondary Phases

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3204
Author(s):  
Jakob Grasserbauer ◽  
Irmgard Weißensteiner ◽  
Georg Falkinger ◽  
Thomas Kremmer ◽  
Peter Uggowitzer ◽  
...  
Keyword(s):  
Cold Rolling ◽  
Texture Evolution ◽  
Secondary Phase ◽  
Homogenization Temperature ◽  
Processing Parameters ◽  
Primary Phase ◽  
Secondary Phases ◽  
Microstructure Formation ◽  
Fe And Mn ◽  
Mn Additions

The increasing demands for Al sheets with superior mechanical properties and excellent formability require a profound knowledge of the microstructure and texture evolution in the course of their production. The present study gives a comprehensive overview on the primary- and secondary phase formation in AlMg(Mn) alloys with varying Fe and Mn additions, including variations in processing parameters such as solidification conditions, homogenization temperature, and degree of cold rolling. Higher Fe alloying levels increase the primary phase fraction and favor the needle-shaped morphology of the constituent phases. Increasing Mn additions alter both the shape and composition of the primary phase particles, but also promote the formation of dispersoids as secondary phases. The size, morphology, and composition of primary and secondary phases is further affected by the processing parameters. The average dispersoid size increases significantly with higher homogenization temperature and large primary particles tend to fragment during cold rolling. The microstructures of the final soft annealed states reflect the important effects of the primary and secondary phase particles on their evolution. The results presented in this paper regarding the relevant secondary phases provide the basis for an in-depth discussion of the mechanisms underlying the microstructure formation, such as Zener pinning, particle stimulated nucleation, and texture evolution, which is presented in Part II of this study.

scholarly journals In situ nuclear-glass corrosion under geological repository conditions

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Mathieu Debure ◽  
Yannick Linard ◽  
Christelle Martin ◽  
Francis Claret
Keyword(s):  
Pure Water ◽  
Secondary Phase ◽  
Predictive Modelling ◽  
Diffusion Experiment ◽  
Secondary Phases ◽  
Glass Corrosion ◽  
Geological Repository ◽  
High Level ◽  
Rock Supports

Abstract Silicate glasses are durable materials but laboratory experiments reveal that elements that derive from their environment may induce high corrosion rates and reduce their capacity to confine high-level radioactive waste. This study investigates nuclear-glass corrosion in geological media using an in situ diffusion experiment and multi-component diffusion modelling. The model highlights that the pH imposed by the Callovo–Oxfordian (COx) claystone host rock supports secondary-phase precipitation and increases glass corrosion compared with pure water. Elements from the COx rock (mainly Mg and Fe) form secondary phases with Si provided by the glass, which delay the establishment of a passivating interface. The presence of elements (Mg and Fe) that sustain glass alteration does not prevent a significant decrease in the glass-alteration rate, mainly due to the limited species transport that drives system reactivity. These improvements in the understanding of glass corrosion in its environment provide further insights for predictive modelling over larger timescales and space.

Simulation of Poly-Disperse Multiphase Systems via Computational Fluid Dynamics

2006 ◽  
Author(s):  
Daniele L. Marchisio ◽  
Marco Vanni ◽  
Antonello A. Barresi ◽  
Giancarlo Baldi
Keyword(s):  
Method Of Moments ◽  
Fluid Model ◽  
Secondary Phase ◽  
Primary Phase ◽  
Momentum Balance ◽  
Multiphase Model ◽  
Secondary Phases ◽  
Discrete Events ◽  
Multiphase Systems ◽  
Two Phases

Multiphase systems, such as sprays and aerosols, are characterized by the existence of a continuous primary phase and a disperse secondary phase. The interaction between the two phases and/or the chemical reactions can affect both composition and characteristic velocity of the primary and secondary phases, as well as the size distribution of the secondary phase. In order to describe these systems, the continuity, mass balance and momentum balance equations as well as additional equations for turbulence, must be solved. Nevertheless if there is the need to account for the evolution of the secondary phase because of continuous and discrete events the population balance equation must be solved. In this work two very efficient ways to cope with these issues will be presented. In particular the use of the quadrature method of moments coupled with the mixture multiphase model, and the multi-fluid model will be presented and discussed.

Densification of Aluminum Nitride Ceramics with CaF2 Additive

2008 ◽  
Vol 368-372 ◽  
pp. 970-972 ◽  
Author(s):  
Yan Xiong ◽  
Zheng Yi Fu ◽  
Hao Wang
Keyword(s):  
Grain Size ◽  
Aluminum Nitride ◽  
Secondary Phase ◽  
Phase Evolution ◽  
Sintered Sample ◽  
Nitrogen Atmosphere ◽  
Microstructural Development ◽  
Secondary Phases ◽  
Nitride Ceramics ◽  
Sem Investigation

Effect of adding up to 5wt% CaF2 on the densification and microstructural development of hot pressed aluminum nitride (AlN) was investigated. SEM investigation showed that the grain size of the sintered sample decreases with the increasing content of CaF2. Secondary-phase evolution paths converge from CA6 to CA phase above 1650°C. TEM micrographs showed that formed secondary phases could evaporate from sintered bodies at higher temperatures in the carbon-containing nitrogen atmosphere and the residuals were mainly distributed at triple grain junctions, keeping direct connections of AlN grains. Translucnet AlN ceramics were prepared using CaF2 additive sintered at 1850°C for 5 h.

Liquid Phase Sintering of SiC-Ceramics

2009 ◽  
Vol 624 ◽  
pp. 91-108 ◽  
Author(s):  
Koushik Biswas
Keyword(s):  
Mechanical Properties ◽  
Liquid Phase ◽  
Grain Boundary ◽  
Secondary Phase ◽  
Phase Evolution ◽  
Liquid Phase Sintering ◽  
Secondary Phases ◽  
Plasma Sintering ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

In view of considerable attention in the development of liquid phase sintered SiC, a comprehensive study of the data on processing, structure and properties seems highly relevant. This article provides a detailed and critical overview of liquid phase sintered silicon carbide ceramics with primary emphasis of grain-boundary/secondary phase evolution, their structure, distribution on the final properties of the sintered materials. The roles of individual additives in developing boundary microstructures will be identified and demonstrated to be critical in optimizing the mechanical properties, including fracture toughness, flexural strength and creep resistance. Numerous methods of structure-properties modification, like in-situ-toughening, -SiC phase transformation, volume of liquid phase, partial/full crystallization of grain-boundary and/or secondary phases are conclusively discussed. Apart from conventional pressureless sintering of SiC, enhanced spark plasma sintering with different oxide and non-oxide sintering additives are also discussed in terms of phase evolution, microstructure and their structure mechanical properties are correlated.

Neptunium-Doped Synroc: Partitioning, Leach Data and Secondary Phase Development

1995 ◽  
Vol 412 ◽  
Author(s):  
Katherine L. Smith ◽  
Mark G. Blackford ◽  
Gregory R. Lumpkin ◽  
Kaye P. Hart ◽  
Brett J. Robinson
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Transmission Electron Microscope ◽  
Secondary Phase ◽  
Secondary Phases ◽  
Phase Development ◽  
Transmission Electron ◽  
Total Differential ◽  
Scanning Electron

AbstractNp-doped Synroc was subjected to modified MCC-1 leach tests in demineralised water at 70°C. Normalised total differential Np leach rates were about 10−4 g m−2 d−1 initially, decreased to about 10−5 g m−2 d−1 after 60 days and stayed approximately constant for periods totalling up to 2283 d. Scanning electron microscope (SEM) and analytical transmission electron microscope (AEM) examination of discs leached for periods totalling 56 d or longer showed that they were covered with crystalline anatase, brookite and ilmenite. The crystalline secondary phases initially nucleated in polishing scratches and on perovskite grains. However, after leaching for a total of 422 d most of the surface was covered. None of the secondary phases contained observable amounts of Np (< 0.2 wt%). These data are discussed in relation to previous work.

scholarly journals Semantička adaptacija frekventnih germanizama u oblasti domaćinstva

2021 ◽  
Vol 32 ◽  
pp. 191-206
Author(s):  
Hatidže Burnić
Keyword(s):  
Comparative Method ◽  
Secondary Phase ◽  
Primary Phase ◽  
German Language ◽  
Secondary Phases ◽  
Contact Linguistics ◽  
Language System ◽  
Semantic Adaptation ◽  
The Moment ◽  
Adaptation Processes

The task of the analysis of adaptation processes is to describe which changes the foreign word has undergone in the primary phase, ie from the moment of borrowing to the formation of the basic form – which in contact linguistics is called replica – and which changes occur in the replica in the secondary phase, ie from the moment of integration in the language system of the recipient further. This paper analyzes the semantic adaptation of frequency Germanisms in the Bosnian language system and focuses on the conceptual field of “household”. The main goal is to determine the semantic changes that words taken from the German language undergo during the download and adaptation to the Bosnian language system. During the analysis, the contact linguistic methodology of Rudolf Filipović was used, in which the adaptation processes are divided into primary and secondary phases of adaptation. The comparative method compared the meanings of German models with the meanings of Bosnian replicas, and the changes were classified into three categories: zero semantic extension, narrowing of meaning and broadening of meaning. Based on the analysis of adaptive changes in the primary phase, it was determined that Germanisms were mostly taken over into the Bosnian language with their specific meanings, but the category of narrowing in the field of meaning was also noted. Unlike the primary adaptation, the secondary adaptation includes changes that occur on the formed replica. These changes are no longer associated with the German language because they are always related only with the Bosnian language system and its rules. This is evidenced by the examples of Germanisms in which in the phase of secondary adaptation there was an expansion of meaning through the use of metaphor, metonymy, pejorization, folk etymology and ellipse.

Tensile and Fracture Behavior of NbSS/Nb5Si3 In Situ Composites Prepared by Arc Melting

2005 ◽  
Vol 297-300 ◽  
pp. 507-514
Author(s):  
Jin Hak Kim ◽  
Tatsuo Tabaru ◽  
Michiru Sakamoto ◽  
Shuji Hanada
Keyword(s):  
Base Composition ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Secondary Phase ◽  
Secondary Phases ◽  
In Situ Composites ◽  
Arc Melting ◽  
Negative Effect ◽  
Base Composite

Nb-base in-situ composites, which have the base composition of Nb-18Si-5Mo-5Hf, have been investigated in microstructure, hardness (Hv*), Young’s modulus (E), tensile properties and fracture behavior. The microstructures of all composites examined consist of NbSS matrix and Nb5Si3 secondary phases. No secondary phase such as Nb2C appeared. The crystal structure of Nb5Si3 is Mn5Si3-type when C replaces 2mol%-Nb, though typical structures of a (Cr5B3-type) and b (W5Si3-type) as in the base composition when W replaces. W addition is effective in increasing Hv* and E of both phases as expected. However, C alloying is somewhat beneficial only in Nb5Si3 with a noticeable negative effect in NbSS. Furthermore, the composite exhibits the highest strength at 1473 K, while the base composite exhibits the highest at room temperature. The fracture behavior is independent of the compositions and it is controlled by cleavage fractures of Nb5Si3, decohesion of NbSS/Nb5Si3 interface and ductile rupture of NbSS depending on the testing temperatures.

Controlling microstructural evolution to in situ toughen and strengthen silicon carbide

1996 ◽  
Vol 54 ◽  
pp. 692-693 ◽  
Author(s):  
Warren J. MoberlyChan ◽  
J. J. Cao ◽  
L. C. DeJonghe
Keyword(s):  
Crack Propagation ◽  
Room Temperature ◽  
Grain Shape ◽  
Secondary Phase ◽  
Fracture Path ◽  
Secondary Phases ◽  
Structural Applications ◽  
Temperature Fracture ◽  
Nonoxide Ceramics

Nonoxide ceramics are desirable for high temperature structural applications, however, they have typically exhibited inferior room temperature fracture toughness. Similar to processing developments to toughen Si3N4, SiC has recently been processed via control of a phase transformation to produce in situ toughened microstructures. An elongated grain shape, coupled with a tortuous fracture path around grains, can provide bridging behind an advancing crack tip, which increases the crack resistance (rising R curve) and halts crack propagation. Most in situ toughened nonoxide ceramics incorporate upwards of 10-20% secondary phase(s), which simplifies crack propagation through this weaker phase to improve toughness, but typically at the expense of substantially reducing strength at high temperatures. The ABC-SiC in this study can be processed with <3% secondary phases and consequently exhibits record toughness and higher strength than commercial (Hexoloy SA) SiC.

Controlled decomposition and reformation of the 2223 phase in Ag-clad (Bi, Pb)2Sr2Ca2Cu3Ox tapes and its influence on the microstructure and critical current density

1996 ◽  
Vol 11 (3) ◽  
pp. 555-564 ◽  
Author(s):  
J. A. Parrell ◽  
Y. Feng ◽  
S. E. Dorris ◽  
D. C. Larbalestier
Keyword(s):  
Liquid Phase ◽  
Critical Current Density ◽  
Relative Density ◽  
Critical Current ◽  
Current Density ◽  
Secondary Phase ◽  
Secondary Phases ◽  
Phase Growth ◽  
Grain Alignment

The decomposition of almost fully reacted (Bi, Pb)2Sr2Ca2Cu3Ox (BSCCO-2223) tapes caused by heating in 1 atm of pure O2 at 825 °C has been studied. It was found that partially decomposing 2223 tapes to a mixture of Bi2Sr2Ca1Cu2Oy, (Ca, Sr)2PbO4, and other secondary phases reduced the critical current density (77 K, 0 T) from ∼20 kA/cm2 to nearly zero. Reheating the tapes in 7.5% O2 restored the 2223 phase and, while there was some degradation of the 2223 grain alignment due to residual secondary phase growth, the critical current density was also restored to nearly its original value. We hypothesize that such a decomposition/reformation process can be useful in increasing the connectivity and relative density of polycrystalline 2223, by encouraging the formation of a liquid phase which heals residual cracks in the BSCCO core.

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