scholarly journals Microstructure and Microanalysis Studies of Copper-Nickel-Tin Alloys Obtained by Conventional Powder Metallurgy Processing

2010 ◽  
Vol 660-661 ◽  
pp. 29-34 ◽  
Author(s):  
Waldemar Alfredo Monteiro ◽  
Juan Alfredo Guevara Carrió ◽  
Terezinha Jocelen Masson ◽  
C.D. Abreu ◽  
I.M. Marques ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Comparative Analysis ◽  
Powder Metallurgy ◽  
Powder Diffraction ◽  
Sintered Density ◽  
Microstructural Analysis ◽  
Microstructural Development ◽  
X Rays ◽  
Powder Diffraction Data ◽  
Tin Alloys

The aim of this article was to analyze the microstructural development in samples of Cu-Ni-Sn alloys (weight %) obtained by powder metallurgy (P/M). The powders were mixed for 1/2 hour. After this, they were pressed, in a cold uniaxial pressing (1000 kPa). In the next step the specimens were sintered at temperatures varying from 650 up to 780°C under vacuum. Secondly, the samples were homogenized at 500oC for several special times. The alloys were characterized by optical microscopy, electrical conductivity and Vickers hardness. X rays powder diffraction data were collected for the sintered samples in order to a structural and microstructural analysis. The comparative analysis is based on the sintered density, densification parameter, hardness, macrostructures and microstructures of the samples.

scholarly journals Structural and Electrical Properties of Copper-Nickel-Aluminum Alloys Obtained by Conventional Powder Metallurgy Method

2010 ◽  
Vol 660-661 ◽  
pp. 41-45 ◽  
Author(s):  
Waldemar Alfredo Monteiro ◽  
Juan Alfredo Guevara Carrió ◽  
C.R. Da Silveira ◽  
E. Vitor ◽  
S.J. Buso
Keyword(s):  
Powder Metallurgy ◽  
Aluminum Alloys ◽  
High Performance ◽  
Sintered Density ◽  
Microstructural Analysis ◽  
Powder Metallurgy Method ◽  
X Rays ◽  
Nickel Aluminum ◽  
Copper Nickel ◽  
Structural And Electrical Properties

This work looked for to search out systematically, in scale of laboratory, copper-nickel-aluminum alloys (Cu-Ni-Al) with conventional powder metallurgy processing, in view of the maintenance of the electric and mechanical properties with the intention of getting electric connectors of high performance or high mechanical damping. After cold uniaxial pressing (1000 kPa), sintering (780oC) and suitable homogenization treatments (500oC for different times) under vacuum (powder metallurgy), the obtained Cu-Ni-Al alloys were characterized by optical microscopy, electrical conductivity, Vickers hardness. X rays powder diffraction data were collected for the sintered samples in order to a structural and microstructural analysis. The comparative analysis is based on the sintered density, hardness, macrostructures and microstructures of the samples.

Crystal structure determination of lithium diborate hydrate, LiB2O3(OH).H2O, from X-ray powder diffraction data collected with a curved position-sensitive detector

1992 ◽  
Vol 25 (5) ◽  
pp. 617-623 ◽  
Author(s):  
D. Louër ◽  
M. Louër ◽  
M. Touboul
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Model ◽  
Rietveld Method ◽  
Position Sensitive Detector ◽  
X Rays ◽  
Sensitive Detector ◽  
Powder Diffraction Data ◽  
Position Sensitive

The crystal structure of lithium diborate hydrate, LiB2O3(OH).H2O, has been solved ab initio and refined by the Rietveld method from powder diffraction data collected with a curved position-sensitive detector (INEL CPS120) using Debye–Scherrer diffraction geometry with monochromatic X-rays. In the first stage the indexing of the powder pattern was performed by the successive dichotomy method from data collected with a diffractometer using Bragg–Brentano geometry. The lattice parameters are a = 9.7984 (10), b = 8.2759 (7) and c = 9.6138 (8) Å and the space group is Pnna. The structural model was obtained from direct methods and two difference Fourier maps. The Rietveld refinement converged to final crystal structure and profile indicators RF = 0.05, RB = 0.05, Rp = 0.03 and Rwp = 0.04. The structure consists of BO4 tetrahedra (T) and BO2(OH) triangles (Δ) sharing corners in order to form infinite chains along [010], with the shorthand notation 3:∞1(Δ + 2T). The particular linkage of the B3O3 rings leads to a new diborate anion {[B2O3(OH)] n− n }, in which two tetrahedral B atoms have an occupation factor of 0.5. Li atoms, tetrahedrally surrounded by four O atoms, three belonging to separate chains and one to a water molecule maintain the cohesion of the structure.

Rietveld Structure Refinement of the Apophyllite Crystals from Deccan Basalt Plateau Using X-ray Powder Diffraction Data

2020 ◽  
Vol 70 (12) ◽  
pp. 4248-4254
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
X Rays ◽  
Powder Diffraction Data ◽  
Deccan Basalt ◽  
X Ray ◽  
Basalt Plateau

The crystal structure of a rare sample of natroapophyllite from Pune district (western India) located in the Deccan Basalt Plateau has been refined using X-Ray powder diffraction data and the Rietveld method. The Rietveld refinement was carried out using the computer program Diffracplus TOPAS 4.1. The pseudo-Voigt (pV) profile function was used for the fit of the peaks. The Rietveld refinement of the analyzed sample in space group Pnnm (No.58): a=8.94771 Å, b=8.98013 Å, c=15.78878 Å, Z=2, confirm the basic natroapophyllite structure. The chemical composition of the apophyllite crystals from Pune region (India) was determined by EDX analysis. The paper presents a new set of the unit cell parameters and fractional coordinates that define the natroapophyllite crystal structure. The quality of the sample analyzed was pristine, the sample being collected from an association of apophyllite-stilbite crystals of centimetric dimensions. Keywords: natroapophyllite, crystal structure, X-rays diffraction, EDX, Rietveld method

scholarly journals Structure of calcium aluminate decahydrate (CaAl2O4·10D2O) from neutron and X-ray powder diffraction data

2007 ◽  
Vol 63 (6) ◽  
pp. 850-861 ◽  
Author(s):  
Axel Nørlund Christensen ◽  
Bente Lebech ◽  
Denis Sheptyakov ◽  
Jonathan C. Hanson
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Calcium Aluminate ◽  
Diffraction Data ◽  
Structure Refinement ◽  
High Alumina ◽  
X Rays ◽  
Powder Diffraction Data ◽  
X Ray

Calcium aluminate decahydrate is hexagonal with the space group P63/m and Z = 6. The compound has been named CaAl2O4·10H2O (CAH10) for decades and is known as the product obtained by hydration of CaAl2O4 (CA) in the temperature region 273–288 K – one of the main components in high-alumina cements. The lattice constants depend on the water content. Several sample preparations were used in this investigation: one CAH10, three CAD10 and one CA(D/H)10, where the latter is a zero-matrix sample showing no coherent scattering contribution from the D/H atoms in a neutron diffraction powder pattern. The crystal structure including the positions of the H/D atoms was determined from analyses of four neutron diffraction powder patterns by means of the ab initio crystal structure determination program FOX and the FULLPROF crystal structure refinement program. Additionally, eight X-ray powder diffraction patterns (Cu Kα1 and synchrotron X-rays) were used to establish phase purity. The analyses of these combined neutron and X-ray diffraction data clearly show that the previously published positions of the O atoms in the water molecules are in error. Thermogravimetric analysis of the CAD10 sample preparation used for the neutron diffraction studies gave the composition CaAl2(OD)8(D2O)2·2.42D2O. Neutron and X-ray powder diffraction data gave the structural formula CaAl2(OX)8(X 2O)2·γX 2O (X = D, H and D/H), where the γ values are sample dependent and lie between 2.3 and 3.3.

Alkali Tin Paraperiodates (MSnIO6): Thermal Analyses, Electrical Conductivity, Infrared, and X-Ray Diffraction Studies

1974 ◽  
Vol 52 (18) ◽  
pp. 3187-3192 ◽  
Author(s):  
Mahadeva Natarajan ◽  
Palepu Ramamurthy ◽  
Etalo A. Secco
Keyword(s):  
Electrical Conductivity ◽  
Powder Diffraction ◽  
Thermal Analyses ◽  
Frequency Region ◽  
Vibrational Modes ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
X Ray ◽  
Initial Mode

Crystalline sodium tin paraperiodate has been prepared; the X-ray powder diffraction data are indexed to the hexagonal system.The thermal analyses, TG and DTA of MSnIO6, where M = NH4, Na, K, Rb, Cs, reveal that the initial mode of decomposition is via partial evolution of I2 and O2.The infrared spectra of these compounds exhibit six well-defined absorption bands. These bands are located within the frequency region characteristic of I—O vibrational modes suggesting a lowering of the normal Oh symmetry for the [IO6]5− species.The electrical conductivity υs. temperature behavior for CsSnIO6 is reported.

FIDDLE. Simultaneous Indexing and Structure Solution from Powder Diffraction Data using a Genetic Algorithm and Correlation Functions

2019 ◽  
Author(s):  
Carmen Guguta ◽  
Jan M.M. Smits ◽  
Rene de Gelder
Keyword(s):  
Genetic Algorithm ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Correlation Functions ◽  
Cross Correlation ◽  
Simultaneous Optimization ◽  
Powder Diffraction Data ◽  
Structure Solution ◽  
Matching Technique

A method for the determination of crystal structures from powder diffraction data is presented that circumvents the difficulties associated with separate indexing. For the simultaneous optimization of the parameters that describe a crystal structure a genetic algorithm is used together with a pattern matching technique based on auto and cross correlation functions.<br>

Specific volume and features of compressibility during the molding of powder-polymer mixtures with wax-polypropylene binder

2019 ◽  
pp. 25-33
Author(s):  
Alexander Muranov ◽  
Alexey Semenov ◽  
Anatoly Kutsbakh ◽  
Boris Semenov
Keyword(s):  
Phase Transition ◽  
Comparative Analysis ◽  
Powder Metallurgy ◽  
Injection Molding ◽  
Polymer Binder ◽  
Polymer Mixture ◽  
Powder Injection ◽  
Polymer Mixtures ◽  
Pvt Data ◽  
Mathematical Processing

The article discusses one of the modern areas of powder metallurgy – the technology of manufacturing shaped parts by the powder injection molding (PIM). For the powder-polymer mixture (feedstock) with a wax-polypropylene binder of the solvent-thermal type of removal by isobaric volume dilatometry, the dependence of PVT state parameters was studied. For each component of the polymer binder, the dependence of pressure on the temperature of phase transition was obtained. As a result of mathematical processing and analysis of PVT data for the feedstock of the studied type, a technological window of parameters has been determined that allows injection molding of «green parts» with minimal volume shrinkage. The results of a comparative analysis of the compaction of feedstock with a polymer binder catalytic and solution-thermal type of removal are presented.

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