A Powder Diffractometry Study of γ'-Phase Formation

1991 ◽  
Vol 6 (2) ◽  
pp. 66-69
Author(s):  
S. Ariely ◽  
G. Kimmel ◽  
S. F. Dirnfeld ◽  
M. Bamberger ◽  
B. Prinz
Keyword(s):  
Phase Formation ◽  
Early Stage ◽  
Pure Nickel ◽  
X Ray Diffraction ◽  
Type Alloy ◽  
Optimal Program ◽  
X Ray ◽  
Nickel Base ◽  
Kinetics Of ◽  
Base Superalloy

AbstractThe kinetics of γ'-phase formation in a Ni-base superalloy were studied. The data (pairs of cps and 2θ) were processed by the deconvolution program (Wiedemann, Unnam and Clark, 1987), which was rewritten in FORTRAN and installed on an IBM/VM and a VAX/VMS host computer. Optimal program parameters were found. Pure nickel was used as a standard. The only evidence obtained from the raw data is that the early stage of the aging process is accompanied by broadening. Deconvolution resolved the peaks into three kinds of diffraction lines: Ni(γ), precipitate (γ'), and undefined lines which have been interpreted as satellites. The results show that our X-ray diffraction lines are composed of the main diffraction lines of nickel-base A1 type alloy and additive satellites. In an advanced stage of aging the satellites assume the typical diffraction pattern of γ' phase.

A Model for Formation and Consumption of Transient Phase

2011 ◽  
Vol 172-174 ◽  
pp. 646-651 ◽  
Author(s):  
Gamra Tellouche ◽  
Khalid Hoummada ◽  
Dominique Mangelinck ◽  
Ivan Blum
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Formation ◽  
Transient Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Proposed Model ◽  
Transient Phases ◽  
Kinetics Of

The phase formation sequence of Ni silicide for different thicknesses is studied by in situ X ray diffraction and differential scanning calorimetry measurements. The formation of a transient phase is observed during the formation of δ-Ni2Si; transient phases grow and disappear during the growth of another phase. A possible mechanism is proposed for the transient phase formation and consumption. It is applied to the growth and consumption of θ-Ni2Si. A good accordance is found between the proposed model and in situ measurement of the kinetics of phase formation obtained by x-ray diffraction and differential scanning calorimetry for higher thickness.

Enhancement of Aurivillius Phase Formation Kinetics in SBT Thin Films using Nanoparticle Seeding

2003 ◽  
Vol 784 ◽  
Author(s):  
Yun-Mo Sung ◽  
Woo-Chul Kwak ◽  
Se-Yon Jung ◽  
Seung-Joon Hwang
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Phase Transformation ◽  
Phase Formation ◽  
X Ray Diffraction ◽  
Aurivillius Phase ◽  
X Ray ◽  
Si Substrates ◽  
Formation Kinetics ◽  
Kinetics Of

ABSTRACTPt/Ti/SiO2/Si substrates seeded by SBT nanoparticles (∼60–80 nm) were used to enhance the phase formation kinetics of Sr0.7Bi2.4Ta2O9 (SBT) thin films. The volume fractions of Aurivillius phase formation obtained through quantitative x-ray diffraction (Q-XRD) analyses showed highly enhanced kinetics in seeded SBT thin films. The Avrami exponents were determined as ∼1.4 and ∼0.9 for unseeded and seeded SBT films, respectively, which reveals different nucleation modes. By using Arrhenius–type plots the activation energy values for the phase transformation of unseeded and seeded SBT thin films were determined to be ∼264 and ∼168 kJ/mol, respectively. This gives a key reason to the enhanced kinetics in seeded films. Microstructural analyses on unseeded SBT thin films showed formation of randomly oriented needle-like crystals, while those on seeded ones showed formation of domains comprised of directionally grown worm-like crystals.

Influence of Mechanical Activation on the Phase Formation in the Synthesis of Cordierite from Talc and Andalusite

2019 ◽  
Vol 798 ◽  
pp. 235-241
Author(s):  
Chatcharin Vairojanakit ◽  
Sujarinee Sinchai
Keyword(s):  
Mechanical Activation ◽  
Phase Formation ◽  
Stoichiometric Composition ◽  
Synthesis Temperature ◽  
Thermal Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Kinetics Of ◽  
Grinding Time

Cordierite is known as a leading candidate material for many applications. In this study, mechanical activation assisted synthesis of cordierite using andalusite as a starting material was attempted and phase formation of powder obtained from the heat treatment of talc-andalusite-silica system was investigated. The stoichiometric composition of cordierite (2MgO·2Al2O3·5SiO2) was prepared and ground in planetary ball mill at the rotational speed of 300 and 500 rpm for 0, 30, 60 and 90 min. The powder mixtures were heat treated in air at the temperature ranging from 1150 to 1350°C for 2 hours. Thermal reaction, phase present and microstructure of the starting materials and synthesized products were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. It was found that cordierite phase increased with the grinding time and speed and synthesis temperature. The kinetics of phase formation in this system were also discussed.

Characterisation of the Structure of Single-Crystal Nickel-Base Superalloys

2010 ◽  
Vol 638-642 ◽  
pp. 2227-2232 ◽  
Author(s):  
Alexander Epishin ◽  
Thomas Link ◽  
Udo Brückner
Keyword(s):  
Single Crystal ◽  
Dendritic Structure ◽  
Experimental Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Kinetics Of ◽  
Morphology Changes ◽  
Sem Investigation

New experimental methods developed by the authors for characterisation of the structure of single-crystal nickel-base superalloys are presented: X-ray diffraction at defined areas of the dendritic structure, none destructive SEM investigation of ’-morphology changes for different creep stresses and times with one specimen, and high resolution SEM investigations of dislocations in the ’-interfaces. Application of these techniques allowed to obtain new results, e.g. about the mosaicity of dendritic subgrains, distribution of the ’-misfit within a single dendrite and kinetics of rafting during creep in the superalloy CMSX-4 in wide temperature and stress ranges.

scholarly journals Cooling Rate Dependent Morphology of the γ' Precipitates in Nickel-Base Superalloy Udimet 500

2011 ◽  
Vol 278 ◽  
pp. 108-113 ◽  
Author(s):  
Mohammad Khalili Savadkoohi ◽  
Ahad Samadi ◽  
Rasoul Salehi
Keyword(s):  
Cooling Rate ◽  
Volume Fraction ◽  
Nickel Base Superalloy ◽  
Air Cooling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rate Dependent ◽  
Compositional Changes ◽  
Nickel Base ◽  
Base Superalloy

The morphology of the γ΄ precipitates during continues cooling of a nickel-base superalloy, Udimet 500, was studied using scanning electron microscopy and X-ray diffraction technique. The samples were full solutioned at 1200oC and then were cooled to ambient temperature under different cooling rates, 15, 1, 0.2, 0.05oC/min and air cooling. The unconstrained γ-γ΄ misfit values for each sample were calculated using the electrolytic extracted γ΄ precipitates. According to the results, by decreasing the cooling rate, not only the size, volume fraction and interparticle spaces of the  precipitates were increased, but also depending on the γ-γ΄ lattice misfits the corresponding  morphology was changed from spherical to cubic, then flower-like and finally dendritic shape. The observations are discussed in view of the compositional changes of γ/γ΄ phases and elastic strain considerations of their interfaces which will be described in detail in the article.

scholarly journals Nanocrystallization and phase formation in Fe73.5Nb3Cu1Si15.5B7 amorphous ribbon under laser heating

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yulia S. Nykyruy ◽  
Stepan I. Mudry ◽  
Yuriy O. Kulyk ◽  
Marcin Lapinski
Keyword(s):  
Phase Formation ◽  
Exposure Time ◽  
Amorphous Ribbon ◽  
Primary Crystallization ◽  
Second Step ◽  
X Ray Diffraction ◽  
Type Alloy ◽  
X Ray ◽  
Nonlinear Temperature ◽  
Time Changes

AbstractLaser-induced local crystallization in Finemet-type alloy was studied using X-ray diffraction, SEM and EDX methods. For investigated conditions of irradiation (wavelength λ = 1.06 µm, laser power density 50 W/cm2), it was found that primary crystallization starts with the formation of the nanocrystalline α-Fe(Si) solid solution at shorter exposure time and the second step crystallization with the nanocrystalline hexagonal H-phase formation occurs in longer exposure time. Changes in the local element concentration were observed at the surface of the irradiated zone and at the ribbon fracture. It was shown that the nonlinear temperature field due to the laser irradiation resulted in changes of the local elements concentration and this feature changed crystallization mechanism of the Finemet-type alloy.

scholarly journals Stable and Metastable Phase Equilibria Involving the Cu6Sn5 Intermetallic

2021 ◽  
Author(s):  
A. Leineweber ◽  
M. Löffler ◽  
S. Martin
Keyword(s):  
Phase Equilibria ◽  
Electron Backscatter Diffraction ◽  
Metastable Phase ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Ordered Phases ◽  
Backscatter Diffraction ◽  
Kinetics Of

Abstract Cu6Sn5 intermetallic occurs in the form of differently ordered phases η, η′ and η′′. In solder joints, this intermetallic can undergo changes in composition and the state of order without or while interacting with excess Cu and excess Sn in the system, potentially giving rise to detrimental changes in the mechanical properties of the solder. In order to study such processes in fundamental detail and to get more detailed information about the metastable and stable phase equilibria, model alloys consisting of Cu3Sn + Cu6Sn5 as well as Cu6Sn5 + Sn-rich melt were heat treated. Powder x-ray diffraction and scanning electron microscopy supplemented by electron backscatter diffraction were used to investigate the structural and microstructural changes. It was shown that Sn-poor η can increase its Sn content by Cu3Sn precipitation at grain boundaries or by uptake of Sn from the Sn-rich melt. From the kinetics of the former process at 513 K and the grain size of the η phase, we obtained an interdiffusion coefficient in η of (3 ± 1) × 10−16 m2 s−1. Comparison of this value with literature data implies that this value reflects pure volume (inter)diffusion, while Cu6Sn5 growth at low temperature is typically strongly influenced by grain-boundary diffusion. These investigations also confirm that η′′ forming below a composition-dependent transus temperature gradually enriches in Sn content, confirming that Sn-poor η′′ is metastable against decomposition into Cu3Sn and more Sn-rich η or (at lower temperatures) η′. Graphic Abstract

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