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.

The Preparation of Nanosized Iron Oxide Using Hydrolysis Enhanced by CuO and their Characterization

2013 ◽  
Vol 320 ◽  
pp. 275-280 ◽  
Author(s):  
Li Hua Lin ◽  
Jian Li ◽  
Long Long Chen
Keyword(s):  
Iron Oxide ◽  
Photoelectron Spectroscopy ◽  
Experimental Results ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Weakly Magnetic ◽  
Nanosized Oxide ◽  
Nanosized Iron

By adding CuO into heated Fe (NO3)3 aqueous solution, a precipitation reaction takes place to form nanosized iron oxide. The product obtained were characterized by transmission electron microscopy (TEM), vibrating sample magnetized (VSM), X-ray diffraction (XRD), energy disperse X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the product is weakly magnetic nanoclusters based on smaller ferrihydrite Fe5O7(OH)·4H2O nanocrystallites. The nanoclusters are of about 40 nm size and absorbed by Fe (NO3)3. The experimental results are attributed to the Fe (NO3)3 hydrolysis reaction being enhanced by CuO as hydrolyte. A new route is proposed for the preparation of nanosized oxide using hydrolysis enhanced.

Analytical Microscopic Analysis of Precipitates in Hastelloy Alloy C-276

1981 ◽  
Vol 39 ◽  
pp. 280-281
Author(s):  
M. Raghavan ◽  
B. J. Berkowitz ◽  
J. C. Scanlon
Keyword(s):  
Microscopic Analysis ◽  
Scanning Transmission Electron Microscope ◽  
Second Phase ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
Corrosion Properties ◽  
X Ray ◽  
Transmission Electron ◽  
Second Phase Particles ◽  
Scanning Transmission

The present investigation was conducted to characterize the second phase particles in Hastelloy C-276 using an analytical Scanning Transmission Electron Microscope in order to understand their effect on the mechanical and Stress Corrosion properties of the alloy. Investigation in our 1aboratoryO) and previous published reports(2-4) have identified two types of precipitation reactions in this alloy. At temperatures in the range of 300-650°C, the alloy precipitates an ordered phase of the type Ni2(Cr, Mo)(1,2). This precipitation reaction is homogeneous with no preferential precipitation at the grain boundaries or twin boundaries. At temperatures above 650°C, several precipitate phases were observed to nucleate heterogeneously at boundaries and using X-ray diffraction techniques, the precipitates were previously identified as the μ, M6C and P phases(3-4). The present investigation was carried out to determine the composition of these second phase particles and this article describes the characterization of these precipitates using X-ray microanalysis and microdiffraction techniques.

scholarly journals Effect of Mg contents on the mechanical proprieties and precipitation kinetics in Al–3.3 wt.% Cu alloy

2018 ◽  
Vol 23 (4) ◽  
pp. 335-345
Author(s):  
Messaoud Fatmi ◽  
A. Ouali ◽  
Amar Djemli ◽  
Tayeb Chihi ◽  
M A Ghebouli ◽  
...  
Keyword(s):  
Discontinuous Precipitation ◽  
Precipitation Reaction ◽  
Precipitation Kinetics ◽  
Transformation Kinetics ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Cu Alloy ◽  
Discontinuous Precipitation Reaction ◽  
Activation Energy Of Crystallization

The effect of additional Mg on the microstructure, mechanical properties, and transformation kinetics during aging in Al–3.3 wt.% Cu alloy was studied. The compositions and microstructure were examined by X-ray diffraction, Differential scanning calorimetry (DSC) and scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The results show that the Mg in the Al–Cu alloy mainly precipitated to the grain boundaries during the process of transformation and formed a ternary Al2CuMg metallic compound and the rate of discontinuous precipitation reaction decreases with increasing concentration of Mg. The activation energy of crystallization was evaluated by applying the Kissinger equation.

scholarly journals Effect of annealing on microstructure, residual stress, and hardness of Al–Ti multilayered films

2001 ◽  
Vol 16 (7) ◽  
pp. 2064-2076 ◽  
Author(s):  
R. Mitra ◽  
A. Madan ◽  
R. A. Hoffman ◽  
W- A. Chiou ◽  
J. R. Weertman
Keyword(s):  
Electron Microscopy ◽  
Residual Stress ◽  
Exothermic Reaction ◽  
X Ray Diffraction ◽  
Multilayered Films ◽  
X Ray ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Bilayer Period ◽  
Evolution Of Microstructure

Al–Ti multilayered films (12 at.% Ti) with bilayer period of 16 nm were deposited by magnetron sputtering. The films were annealed in vacuum at 350 or 400 °C between 2 and 24 h. During annealing, a diffusion-controlled chemical reaction between Al and Ti layers led to Al3Ti precipitation. Differential thermal analysis studies showed an exothermic reaction associated with Al3Ti formation, taking place between 320 and 390 °C, depending on the heating rate. The evolution of microstructure with annealing was examined with transmission electron microscopy and x-ray diffraction. The hardness and residual stress of the films in the as-deposited and annealed conditions were studied in relation to the microstructural changes on annealing.

A Second Modification of Mercury(I) Orthoarsenate(V): Preparation and Crystal Structure of β-(Hg2)3(AsO4)2

2004 ◽  
Vol 59 (8) ◽  
pp. 859-864 ◽  
Author(s):  
Matthias Weil
Keyword(s):  
Crystal Structure ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
Data Set ◽  
Group Type ◽  
Light Yellow ◽  
Accuracy And Precision ◽  
Diffusion Controlled ◽  
Structure Factors ◽  
Controlled Precipitation

AbstractLight-yellow crystals of a second modification of mercury(I) orthoarsenate(V), β-(Hg2)3(AsO4)2, were obtained during a diffusion-controlled precipitation reaction starting from diluted solutions of Hg2(NO3)2, Hg(NO3)2, and H3AsO4. The crystal structure was determined from a single crystal X-ray diffraction data set. The previously reported crystal structure of synthetic chursinite, α-(Hg2)3(AsO4)2, has also been re-investigated and refined with better accuracy and precision. Both phases crystallize in space group type P21/c (no. 14) [α- (β -): Z = 2 (4), a = 8.7915(6) (10.2034(18)), b = 5.0699(4) (8.5875(14)), c = 15.6839(10) (13.5172(19)) Å , β = 128.761(1) (101.016(3))°, 1661 (3528) structure factors, 74 (146) parameters, RF2 > 2σ (F2)] = 0.0195 (0.0492)] and are made up from Hg22+ dumbbells and AsO43− tetrahedra as the main building units, but the topologies of the structures are quite different.

scholarly journals Reação de precipitação de Ag na liga Cu-8%Al-6%Ag

2018 ◽  
Vol 33 (1) ◽  
pp. 63
Author(s):  
Ricardo Alexandre Galdino Da Silva ◽  
Aroldo Geraldo Magdalena ◽  
Thaisa Mary Carvalho
Keyword(s):  
Electron Microscopy ◽  
Reaction Rate ◽  
Ageing Time ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Diffusion Controlled ◽  
Diffraction Patterns ◽  
Scanning Electron

Ag precipitation reaction in the Cu-8wt.%Al-6wt.%Ag alloys was studied using microhardness measurements with temperature and ageing time, X-ray diffraction patterns (DRX), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results obtained showed that the mechanism of Ag precipitation reaction is an Ag diffusion controlled process and reaction rate reaches a maximum at about 500ºC.

A Study of Parameters that Influence Growth and Stability of the (Bi1−xPbx)2Sr2Ca2Cu3Oy Phase

1992 ◽  
Vol 275 ◽  
Author(s):  
J. S. Luo ◽  
N. Merchant ◽  
V. A. Maroni ◽  
D. M. Gruen ◽  
B. S. Tani ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Fine Powder ◽  
X Ray Diffraction ◽  
Time Data ◽  
X Ray ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Heat Treated ◽  
Limited Temperature ◽  
Precursor Powders

ABSTRACTThe growth and stability of the (Bi1-xPbx)2Sr2Ca2Cu3Oy (Bi-2223) phase contained in silver-sheathed wires has been investigated by a combination of x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and transmission electron microscopy. Silver tubes loaded with Bi-2223 precursor powders were processed into filaments using established metallurgical techniques. The filaments were then heat-treated at selected temperatures (800 to 845°C) for a range of times (10 to 6000 min) in a 7.5% oxygen atmosphere. From these studies it has been possible to investigate the time-temperature-oxygen pressure domains wherein Bi2Sr2CaCu2O8 (Bi-2212) + second phases transform to Bi-2223. Fractional conversion (Bi-2212 --> Bi-2223) versus time data show good conformance to the kinetic model for a diffusion-controlled reaction at the interface between thin sheets and a fine powder or a fluid. Quenching experiments also reveal that the Bi-2223 phase is stable in a limited temperature interval between 810 and 830°C.

Hydrothermal Synthesis of Tungsten Oxide Nanoparticles

2012 ◽  
Vol 268-270 ◽  
pp. 176-179 ◽  
Author(s):  
Yang Rong Yao ◽  
Rong Ma ◽  
Xu Chun Song
Keyword(s):  
Electron Microscopy ◽  
Tungsten Oxide ◽  
Oxide Nanoparticles ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Tungsten Oxide Nanoparticles ◽  
Hcl Solution ◽  
Scanning Electron

In the present paper, the tungsten oxide nanoparticles were fabricated via a hydrothermal treatment of the H2WO4 precursors. The H2WO4 precursors were prepared by method of precipitation reaction between aqueous Na2WO4 and HCl solution. The products are characterized in detail by multiform techniques: scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray analysis. The results show that products are WO3 nanoparticles with diameter of about 100-150 nm.

Early Instability Phenomena of IN792 DS Superalloy

2016 ◽  
Vol 879 ◽  
pp. 2026-2031 ◽  
Author(s):  
Roberto Montanari ◽  
Oriana Tassa ◽  
Alessandra Varone
Keyword(s):  
Electron Microscopy ◽  
Dynamic Modulus ◽  
Room Temperature ◽  
Average Distance ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
X Ray ◽  
Microstructure Stability ◽  
Transmission Electron

Microstructure stability of the directionally solidified Ni base IN792 superalloy has been investigated by Mechanical Spectroscopy (MS), i.e. internal friction (IF) and dynamic modulus measurements. Repeated IF test runs from room temperature to 1173 K have been carried out on the same samples and a Q-1 maximum has been always observed above 700 K. Its position does not depend on the resonance frequency. After each run the values of modulus and Q-1 at room temperature change indicating that a progressive irreversible transformation occurs. Damping phenomena have been attributed to the rearrangement of dislocation structures in disordered matrix which modifies dislocation density and average distance of pinning points. The results are supported by X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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