scholarly journals Effect of lead content on phase evolution and microstructural development in Ag-clad Bi-2223 composite conductors

1997 ◽  
Author(s):  
N.N. Merchant ◽  
V.A. Maroni ◽  
A.K. Fischer ◽  
S.E. Dorris ◽  
W. Zhong ◽  
...  
Keyword(s):  
Phase Evolution ◽  
Lead Content ◽  
Microstructural Development ◽  
Composite Conductors

Synthesis, Processing and Phase Evolution of TiN/TiB2 Composites From Polymeric Precursors

1992 ◽  
Vol 286 ◽  
Author(s):  
M. Nowakowski ◽  
K. Su ◽  
L. Sneddon ◽  
D. Bonnell
Keyword(s):  
Phase Evolution ◽  
High Yield ◽  
Microstructural Development ◽  
Synthetic Route ◽  
Polymeric Precursors

ABSTRACTA high yield synthetic route to TiN/TiB2 nanocomposites based upon polymeric precursors has been developed. The phase evolution and microstructural development have been characterized and related to preliminary measurements of properties, i.e. hardness. The observations indicate the existence of TiN-TiB2, TiN-BN, and TiB2-BN subsolidus compatibilities.

Raman microscopy examination of phase evolution in Bi(Pb)–Sr–Ca–Cu–O superconducting ceramics

1997 ◽  
Vol 12 (5) ◽  
pp. 1195-1204 ◽  
Author(s):  
K. T. Wu ◽  
A. K. Fischer ◽  
V. A. Maroni ◽  
M. W. Rupich
Keyword(s):  
Spatial Distribution ◽  
Phase Evolution ◽  
Exciting Radiation ◽  
Raman Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Composite Conductors ◽  
Superconducting Ceramics ◽  
Complementary Techniques ◽  
Microscopy Examination

Raman microspectroscopy (RMS) and imaging Raman microscopy (IRM) were used to probe the composition and spatial distribution of chemical phases in Bi(Pb)–Sr–Ca–Cu–O (BSCCO) ceramic superconductor powders and silver-BSCCO composites. The Raman techniques were used to identify various phases, including alkaline earth cuprates, CuO, Bi-2212, Bi-2223, and Pb-containing phases. Changes in the Ca/Sr ratios in (Ca, Sr)2CuO3 phases were distinguished by differences in orientation with respect to polarization of the exciting radiation. Variations were observed in the content and distribution of lead in various phases formed during intermediate stages of the thermal processing of composite conductors. The spatial distribution of the various phases detected in powder and composite conductors was established to a resolution of a few microns by collecting images of the Raman scattering at wavelengths corresponding to the signature peaks of the observed phases. Reference Raman spectra of the major phases observed in the BSCCO system are also reported. The Raman techniques, when combined with complementary techniques, such as x-ray diffraction and electron microscopy, can provide valuable information about the reaction paths and mechanisms of the high temperature BSCCO superconducting ceramics.

scholarly journals Influence of molybdenum content on the microstructure of spark plasma sintered titanium alloys

2021 ◽  
Vol 1 (1) ◽  
pp. 41-47
Author(s):  
M. Saravana Kumar ◽  
S. Rashia Begum ◽  
M. Vasumathi ◽  
Chinh Chien Nguyen ◽  
Quyet Van Le
Keyword(s):  
Relative Density ◽  
Phase Evolution ◽  
Microstructural Development ◽  
Sintered Titanium ◽  
Sintering Process ◽  
Plasma Sintering ◽  
The Matrix ◽  
Molybdenum Addition ◽  
Spark Plasma ◽  
Mo Content

Five titanium-based alloys containing 4, 8, 12, 16, and 20 wt% molybdenum additive were fabricated by spark plasma sintering process at 1200 ˚C. The samples were scrutinized in terms of relative density, phase evolution, and microstructural development. The relative density reached 99.9% with the molybdenum addition up to 16 wt% but slightly dropped in the sample with 20 wt% additive. In the specimens with 4 wt% Mo, molybdenum solved completely in the matrix and three different phase morphologies were observed, namely continuous α-Ti, laminar α-Ti, and very thin laminar β-Ti. With increasing Mo content to 20 wt%, widespread single β-Ti appeared alongside remained Mo and α-Ti. Ductile fracture mode was dominant in the samples with low Mo contents whilst it changed to brittle in the specimens with higher content of molybdenum.

Microstructural development in solution-derived PZT thin films

1994 ◽  
Vol 52 ◽  
pp. 578-579
Author(s):  
T. J. Headley ◽  
B. A. Tuttle ◽  
J. A. Voigt ◽  
J. R. Michael
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Capital Investment ◽  
Perovskite Phase ◽  
Amorphous Film ◽  
Phase Evolution ◽  
Lead Zirconate ◽  
Solution Chemistry ◽  
Microstructural Development ◽  
Pzt Thin Films

Lead zirconate titanate (PZT) thin films are of technological interest for a variety of electronic and optical applications such as nonvolatile memories, decoupling capacitors, infrared detectors, and optical storage media. Fabrication of PZT films by solution deposition techniques is attractive because of uniform, stoichiometric control at the molecular level, ease of processing, and both low capital investment and total cost. Control of phase evolution, microstructure, crystallite size and orientation, and ferroelectric domain assemblage during processing is essential to optimize electrical and/or optical properties of the films. Factors which play a major role in controlling these parameters are details of the solution chemistry and mixing, thermal processing, Pb stoichiometry, Zr/Ti ratio, and substrate characteristics. Electron microscopy techniques have been used extensively to correlate microstructural features with film processing parameters as will be emphasized in this presentation.As annealing temperature is increased, phase evolution in PZT thin films typically proceeds from amorphous to pyrochlore to the ferroelectric perovskite phase. Fine-grained pyrochlore crystallizes from the amorphous film at low annealing temperatures and also precedes crystallization of the perovskite phase at higher temperatures. There is evidence that the Zr/Ti stoichiometry influences the microstructure of the amorphous-to-pyrochlore transformation.

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.

Perplastic SiAION—A Bird's Eye View of Silicon Nitride Ceramics

1992 ◽  
Vol 287 ◽  
Author(s):  
I-Wei Chen ◽  
Shyh-Lung Hwang
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Large Strain ◽  
Phase Relationship ◽  
Phase Evolution ◽  
Low Flow ◽  
Microstructural Development ◽  
Oxide Melt ◽  
Grain Boundary Characteristics ◽  
Boundary Characteristics

ABSTRACTSuperplastic Sialons have very fine microstructures containing submicron grains and transient phases. Fabrication of these materials requires processing at relatively low temperatures. As a result, different stages of phase evolution, including oxide melt formation, nitride dissolution, a′ and β′-SiAlON nucleation, and Sialon growth with and without concurrent deformation, can be captured in the development of these materials. In addition, only very low flow stresses are required for large strain deformation which, in turn, allows grain boundary and liquid phase processes to be manifested in the deformation behavior. Highlights of investigation of these aspects are reviewed here to shed light on the phase relationship, microstructural development, and grain boundary characteristics of silicon nitride.

Transmission Electron Microscopy of Pb-doped Bi2Sr2Ca2Cu30x /Ag composite conductors prepared by the two-powder process: The effect of lead addition on critical current and microstructure

1994 ◽  
Vol 52 ◽  
pp. 798-799
Author(s):  
J. S. Luo ◽  
S. E. Dorris ◽  
M. T. Lanagan ◽  
V. A. Maroni
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Critical Current ◽  
Phase Evolution ◽  
Specific Method ◽  
X Ray ◽  
Transmission Electron ◽  
Composite Conductors ◽  
Current Densities ◽  
Lead Addition

Recent studies indicate that a more uniform and more fully reacted Pb-doped Bi2Sr2Ca2Cu3Ox (Bi-2223)phase can be reproducibly obtained within silver sheaths using a two-powder precursor in which the formation of Bi-2223 primarily involves reaction between lead-doped Bi2Sr2CaCu2Oz (Bi-2212) and other non-superconducting phases. In particular, the specific method of introducing lead was reported to significantly influence the phase evolution and superconducting properties of Bi-2223/Ag composite conductors.2 Composites made from lead-doped Bi-2212, where lead is fully incorporated into the Bi-2212 phase prior to its conversion to Bi-2223, exhibit sharper transition temperatures and higher critical current densities than those where lead is added in the form of non-superconducting PbO or Ca2PbO4 phases (Fig. I).2 In this paper, we present a combined investigation by transmission electron microscopy(TEM) and energy dispersive x-ray spectroscopy (EDX) of the composition and microstructure of the (Bi-2223)/Ag composite conductors. The observed differences are discussed with respect to the measured electrical properties.

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