Interphase interfaces in Nio-Zro2 (Cao) eutectic

1987 ◽  
Vol 45 ◽  
pp. 292-293
Author(s):  
Vinayak P. Dravid
Keyword(s):  
Orientation Relationship ◽  
Transverse Section ◽  
Bulk Material ◽  
Preliminary Investigation ◽  
Growth Direction ◽  
Directionally Solidified ◽  
X Ray ◽  
Two Phases ◽  
Directionally Solidified Eutectics ◽  
Interfacial Plane

Directionally solidified eutectics (DSEs) of oxide-oxide components offer many advantages over the conventional bi-crystal specimens for interface studies. The two phases in the DSE grow in unison with a well-defined orientation relationship and offer a wide spatial range of crystallographically similar interfaces. A preliminary investigation has been carried out to characterize interphase interfaces in the DSE system NiO-ZrO2 (CaO). The transverse section of the DSE consists of alternate lamellae of cubic NiO and CaO-stabilized cubic ZrO2, as shown in Figure 1. The orientation relationship (OR) from the selected area diffraction (SAD) pattern (Figure 2) was observed to be:growth direction //[011]NiO//[001]ZrO2 and interfacial plane //(111)NiO//(100)Zr02The above OR was predominant in the bulk material and is consistent with x-ray results, but at lamellar termination/faults the OR was observed to be:

scholarly journals Preparation and properties of natural rubber/organo-montmorillonite: from lab samples to bulk material

2014 ◽  
Vol 33 (2) ◽  
pp. 249 ◽  
Author(s):  
Aleksandra Ivanoska-Dacikj ◽  
Gordana Bogoeva-Gaceva ◽  
Aleksandra Buzarovska ◽  
Igor Gjorgjiev ◽  
Luljeta Raka
Keyword(s):  
Natural Rubber ◽  
Dynamic Testing ◽  
Bulk Material ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Elongation At Break ◽  
X Ray ◽  
Roll Mill ◽  
Two Phases ◽  
Effective Reinforcement

<p>Focusing on application aspects of the rubber nanocomposites and the production and testing of industrial-sized samples, this study was performed in two phases. First, natural rubber (NR)/organo-montmorillonite (OMMT) nanocomposites containing 2–14 phr OMMT were prepared on a laboratory-sized two-roll mill. The vulcanization behavior and mechanical properties of NR/OMMT composites were compared with a referent NR compound containing 60 phr carbon black (N330) as a reinforcing filler. The x-ray diffraction (XRD) analyses showed a predominant intercalated structure for all OMMT nanocomposites. As a result, the organoclay behaved as an effective reinforcement for NR, even at loadings as low as 2 phr. This nanocomposite exhibited an improvement in tensile strength of 29% and in elongation at break of 61% in comparison with the referent NR/N330 compound. With the estimated optimal filler content, in the second phase, bulk NR/OMMT-5/steel samples were successfully produced for dynamic testing. The dynamic moduli were investigated by the method of forced vibrations. Compared to the NR/N 330 samples, NR/OMMT-5 samples showed improved hysteresis, with very low dissipating energy per cycle and significantly reduced Mullins effect.</p>

Coupled Peritectic Growth of the α- and Γ- Phases in Binary Titanium Aluminides

1995 ◽  
Vol 398 ◽  
Author(s):  
F. Meissen ◽  
P. Busse ◽  
J. Laakmann
Keyword(s):  
Peritectic Reaction ◽  
Titanium Aluminides ◽  
Eutectic Growth ◽  
Theoretical Models ◽  
Growth Direction ◽  
Directionally Solidified ◽  
Equilibrium Solidification ◽  
Two Phases ◽  
Oriented Parallel ◽  
Coupled Growth

ABSTRACTCoupled growth during three phase equilibrium solidification is well known from directionally solidified eutectic systems, and was recently generated in monotectic systems. Several theories predict a stationary peritectic reaction and coupled growth of the properitectic and the peritectic phases therefore should be possible. In spite of these theories coupled growth has not been observed up to now. The TiAl system was selected for further investigation on this topic because of its technical relevance and the fact that it meets the condition mentioned for coupled growth.In a Bridgman laboratory furnace, TiAl with 53.4 at.% Al was directionally solidified with solidification rates v between 0.025 mm/min and 0.1 mm/min and a temperature gradient up to 20 K/mm. The resulting microstructures, analyzed using optical and scanning microscopy with EDX and WDX, consist of two phases parallel to the growth direction. At v = 0.05 to 0.1 mm/min, the alloy solidifies as properitectical α, which subsequently eutectoidally transforms to a substructure of α2-Ti3Al and γ-TiAl, and peritectic γ. The lamellar α2/γ-substructure is oriented parallel to the growth direction.The experimental results were compared with the existing theoretical models of a stationary peritectic reaction and the possibility of metastable eutectic growth was discussed.

Eu-doped Yttria and Lutetia Thin Films Grown on Sapphire by PLD

2004 ◽  
Vol 817 ◽  
Author(s):  
S. Bär ◽  
H. Scheife ◽  
G. Huber ◽  
J. Gonzalo ◽  
A. Perea ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Bulk Material ◽  
Stoichiometric Composition ◽  
Growth Direction ◽  
X Ray Diffraction ◽  
Excitation Spectra ◽  
X Ray ◽  
Crystalline Films ◽  
20 Nm

AbstractThis paper focuses on the preparation and characterization of crystalline thin films of rare-earth-doped sesquioxides (Y2O3 and Lu2O3) grown by pulsed laser deposition on single-crystal (0001) sapphire substrates. The crystal structure of the films (thicknesses between 1 nm and 500 nm) was determined by X-ray diffraction and surface X-ray diffraction analysis. These measurements show that the films were highly textured along the <111> direction. Using Rutherford backscattering analysis the correct stoichiometric composition of the films could be proved. The surface morphology of the thin films has been studied using atomic force microscopy. Crystalline films show a triangular surface morphology, which is attributed to the <111> growth direction. The emission and excitation spectra of the Eu-doped films down to a thickness of 100 nm look similar to those of the corresponding crystalline bulk material, whereas films with a thickness ≤ 20 nm show a completely different emission behaviour.

scholarly journals Phase Formation in the Pt/Inp Thin Film System

1989 ◽  
Vol 148 ◽  
Author(s):  
D. A. Olson ◽  
K. M. Yu ◽  
J. Washburn
Keyword(s):  
Orientation Relationship ◽  
Metal Films ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
X Ray ◽  
Thin Film System ◽  
Transmission Electron ◽  
Two Phases ◽  
Inp Substrates

ABSTRACTInP substrates with 40nm metal films of Pt were encapsulated in SiO2, and isochronally annealed up to 600°C in flowing forming gas. The composition and morphology of the phases that formed were studied using x-ray diffraction, Rutherford Backscattering, and transmission electron microscopy.Results show that the Pt/InP system begins interacting at 300°C. TEM analysis of the 350°C anneal shows unreacted Pt and and additional polycrystalline phases, with no observed orientation relationship with the substrate. The Pt layer has been completely consumed by 400°C, with a uniform reacted layer indicated by RBS. At high temperatures (between 500°C and 600°C), the reaction products are PtIn2 and PtP2. The two phases show a tendency for phase separation, with a higher concentration of PtP2 at the InP/reacted layer interface. The phosphide phase also shows a preferred orientation relationship with the substrate.

scholarly journals Deformation and fracture of a directionally solidified NiAl–28Cr–6Mo eutectic alloy

1995 ◽  
Vol 10 (5) ◽  
pp. 1159-1170 ◽  
Author(s):  
X.F. Chen ◽  
D.R. Johnson ◽  
R.D. Noebe ◽  
B.F. Oliver
Keyword(s):  
Room Temperature ◽  
Growth Direction ◽  
Temperature Deformation ◽  
Dislocation Network ◽  
Directionally Solidified ◽  
Lamellar Morphology ◽  
Nial Phase ◽  
Deformation And Fracture ◽  
Eutectic Morphology ◽  
Two Phases

A directionally solidified alloy based on the NiAl-(Cr, Mo) eutectic was examined by transmission and scanning electron microscopy to characterize the microstructure and room temperature deformation and fracture behavior. The microstructure consisted of a lamellar morphology with a 〈111〉 growth direction for both the NiAl and (Cr,Mo) phases. The interphase boundary between the eutectic phases was semicoherent and composed of a well-defined dislocation network. In addition, a fine array of coherent NiAl precipitates was dispersed throughout the (Cr, Mo) phase. The eutectic morphology was stable at 1300 K with only coarsening of the NiAl precipitates occurring after heat treatment for 1.8 ks (500 h). Fracture of the aligned eutectic is characterized primarily by a crack bridging/renucleation mechanism and is controlled by the strength of the semicoherent interface between the two phases. However, contributions to the toughness of the eutectic may arise from plastic deformation of the NiAl phase and the geometry associated with the fracture process.

Microstructures and Mechanical Properties of in-situ V-V3B2 Composites

2006 ◽  
Vol 980 ◽  
Author(s):  
Sujing Xie ◽  
Easo P. George
Keyword(s):  
Tensile Tests ◽  
Eutectic Structure ◽  
Growth Direction ◽  
Solid Solution Alloy ◽  
Directionally Solidified ◽  
Arc Melting ◽  
Composite Microstructure ◽  
Two Phases ◽  
Microstructural Examination

AbstractA series of binary V-B alloys, with compositions spanning the eutectic, were produced by arc melting and drop casting. Microstructural examination revealed that the fully eutectic structure occurs at V-11B rather than V-15B as reported in the V-B phase diagram (all compositions in at.%). The V-11B eutectic was directionally solidified in an optical floating zone furnace, resulting in a composite microstructure consisting of a V matrix and flake or trigonal shaped V3B2 phase. The boride flake spacing (ë) decreases with increasing growth rate (R), following the relation ë2.56R=C, where C is a constant. TEM observations showed that the orientation relationship between the V and V3B2 phases is given by: [001]V // [001]V3B2 and (100)V // (100)V3B2. The growth direction and the V/V3B2 interface are parallel to the [001] direction and (100) planes in the two phases, respectively. Tensile tests were used to investigate the temperature dependence of the strength and ductility of the composite. At temperatures to 600°C, the yield strength of the eutectic is about 140 MPa higher than that of a commonly used vanadium solid-solution alloy, V-4Cr-4Ti. Surprisingly, the eutectic shows 5% tensile ductility at room temperature which increases to 10% as the test temperature is raised to 800°C.

Determination of interface width using EELS fine structure changes

1991 ◽  
Vol 49 ◽  
pp. 730-731
Author(s):  
Vinayak P. Dravid ◽  
M.R. Notis ◽  
C.E. Lyman
Keyword(s):  
Fine Structure ◽  
Materials Science ◽  
Input Parameter ◽  
Core Loss ◽  
Directionally Solidified ◽  
Interface Width ◽  
Structure Changes ◽  
Important Input ◽  
Directionally Solidified Eutectics

The concept of interfacial width is often invoked in many materials science phenomena which relate to the structure and properties of internal interfaces. The numerical value of interface width is an important input parameter in diffusion equations, sintering theories as well as in many electronic devices/processes. Most often, however, this value is guessed rather than determined or even estimated. In this paper we present a method of determining the effective structural and electronic- structural width of interphase interfaces using low- and core loss fine structure effects in EELS spectra.The specimens used in the study were directionally solidified eutectics (DSEs) in the system; NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2(ss). EELS experiments were carried out using a VG HB-501 FE STEM and a Hitachi HF-2000 FE TEM.

A TEM investigation of a hyper-eutectic lead-tin alloy

1988 ◽  
Vol 46 ◽  
pp. 562-563
Author(s):  
John A. Sutliff
Keyword(s):  
Volume Diffusion ◽  
Eutectic Mixture ◽  
Precipitation Reaction ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Discontinuous Precipitation Reaction ◽  
Controlled Precipitation

Near-eutectic Pb-Sn alloys are important solders used by the electronics industry. In these solders, the eutectic mixture, which solidifies last, is the important microstructural consituent. The orientation relation (OR) between the eutectic phases has previously been determined for directionally solidified (DS) eutectic alloys using x-ray diffraction or electron chanelling techniques. In the present investigation the microstructure of a conventionally cast, hyper-eutectic Pb-Sn alloy was examined by transmission electron microscopy (TEM) and the OR between the eutectic phases was determined by electron diffraction. Precipitates of Sn in Pb were also observed and the OR determined. The same OR was found in both the eutectic and precipitation reacted materials. While the precipitation of Sn in Pb was previously shown to occur by a discontinuous precipitation reaction,3 the present work confirms a recent finding that volume diffusion controlled precipitation can also occur.Samples that are representative of the solder's cast microstructure are difficult to prepare for TEM because the alloy is multiphase and the phases are soft.

Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

1990 ◽  
Vol 48 (2) ◽  
pp. 314-315
Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Equilibrium Phase ◽  
Icosahedral Symmetry ◽  
Ion Microprobe ◽  
X Ray ◽  
Cu Alloys ◽  
Two Phases ◽  
The University ◽  
Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

Sign in / Sign up

Export Citation Format

Share Document