scholarly journals Dissolution of the Primary γ′ Precipitates and Grain Growth during Solution Treatment of Three Nickel Base Superalloys

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1921
Author(s):  
Karen Alvarado ◽  
Ilusca Janeiro ◽  
Sebastian Florez ◽  
Baptiste Flipon ◽  
Jean-Michel Franchet ◽  
...  
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Solution Treatment ◽  
Dissolution Kinetics ◽  
Second Phase ◽  
Stable States ◽  
Size Evolution ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Kinetics Of

Second phase particles (SPP) play an essential role in controlling grain size and properties of polycrystalline nickel base superalloys. The understanding of the behavior of these precipitates is of prime importance in predicting microstructure evolutions. The dissolution kinetics of the primary γ′ precipitates during subsolvus solution treatments were investigated for three nickel base superalloys (René 65, AD730 and N19). A temperature-time codependency equation was established to describe the evolution of primary γ′ precipitates of each material using experimental data, the Thermo-Calc software and the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model. The dissolution kinetics of precipitates was also simulated using the level-set (LS) method and the former phenomenological model. The precipitates are represented using an additional LS function and a numerical treatment around grain boundaries in the vicinity of the precipitates is applied to reproduce their pinning pressure correctly. Thus, considering the actual precipitate dissolution, these simulations aim to predict grain size evolution in the transient and stable states. Furthermore, it is illustrated how a population of Prior Particle Boundaries (PPB) particles can be considered in the numerical framework in order to reproduce the grain size evolution in the powder metallurgy N19 superalloy. The proposed full-field strategy is validated and the obtained results are in good agreement with experimental data regarding the precipitates and grain size.

Effect of Microstructure on the Dissolution Kinetics of Copper Thin Films in Dilute Aqueous Solutions of Cupric Chloride

1993 ◽  
Vol 323 ◽  
Author(s):  
L. Harper Walsh ◽  
N. B. Feilchenfeld ◽  
J. A. Schwarz
Keyword(s):  
Grain Size ◽  
Grain Orientation ◽  
Dissolution Kinetics ◽  
Surface Region ◽  
Practical Method ◽  
Reaction Rates ◽  
Near Surface ◽  
Dilute Aqueous Solutions ◽  
Microelectronics Industry ◽  
Kinetics Of

ABSTRACTMicrostructural differences in copper deposited by four techniques commonly used in the microelectronics industry were previously reported. [1] The reaction rates were predicted using either grain size or grain orientation as the dominant microstructure characteristic. A practical method to monitor copper speciation was developed.[2] This technique was used to measure the reaction rates for the different copper films under two different etching conditions. The results are explained using grain size, grain orientation and near surface region composition.

scholarly journals Influence of Grain Refinement on Oxidation Behavior of Two-Phase Cu–Cr Alloys at 973–1,073 K in Air

2016 ◽  
Vol 35 (10) ◽  
pp. 1005-1011
Author(s):  
T. J. Pan ◽  
J. Chen ◽  
Y. X. He ◽  
W. Wei ◽  
J. Hu
Keyword(s):  
Grain Size ◽  
Spatial Distribution ◽  
Oxidation Behavior ◽  
Second Phase ◽  
Two Phase ◽  
Reactive Component ◽  
Parabolic Law ◽  
Second Phase Particles ◽  
Kinetics Of ◽  
Lower Oxidation

AbstractThe oxidation behavior of grain-refined Cu–7.0 Cr alloy (GR Cu–7.0 Cr) in air at 973–1,073 K was investigated in comparison with normal casting Cu–7.0 Cr alloy (CA Cu–7.0 Cr). The oxidation of CA Cu–7.0 Cr alloy nearly followed parabolic law, while the oxidation kinetics of GR Cu–7.0 Cr slightly deviated from parabolic law. Both alloys almost produced multi-layered scales consisting of the outer layer of CuO and the inner layer of mixed Cr2O3 and Cu2O oxides plus internal oxidation zones of chromium. The grain-refined Cu–7.0 Cr alloy produced a more amount of Cr2O3 in the inner layer of the scale, and thus was oxidized at much lower oxidation rate than that of CA Cu–7.0 Cr with normal grain size. The experimental results indicated that the differences in oxidation behavior between two alloys may be ascribed to the different size and spatial distribution of the second-phase particles and the reactive component contents in localized zone.

scholarly journals Acidic leaching of iron from Kaoje Goethite ore by hydrochloric acid: Kinetics modelling

2020 ◽  
Vol 39 (3) ◽  
pp. 800-806
Author(s):  
K.I. Ayinla ◽  
A.A. Baba ◽  
S. Girigisu ◽  
O.S. Bamigboye ◽  
B.C. Tripathy ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Acid Leaching ◽  
Dissolution Kinetics ◽  
Second Phase ◽  
Low Grade ◽  
Iron And Steel ◽  
Kinetics Modelling ◽  
Shrinking Core ◽  
Hcl Concentration ◽  
Kinetics Of

Considering the recent focus of the Nigeria Government to grow and develop the nation’s economy through the solid minerals sector reform, this study has been devoted to the kinetics of a Nigerian goethite ore by hydrochloric acid leaching for improved iron and steel industries applications. This study was performed in three different phases. In the first phase, acidic leaching of iron from a goethite ore was examined and the influence of the operating variables including: HCl concentration, leaching temperature, stirring speed and particle sizes was examined experimentally. The optimum condition was found to be HCl concentration of 1.81M, temperature of 80°C, 200 rpm stirring speed and particle size 0.09 μm for iron in the range of investigated parameters. Under those conditions, the highest iron recovery was obtained to be 95.67 %. In the second phase, the dissolution kinetics of iron was evaluated by the shrinking core models. The finding reveals that diffusion through the fluid was the leaching kinetics rate controlling step of the iron. The activation energy (Ea) was found to be 14.54 kJmol-1 for iron. Equation representing the leaching kinetic of iron was achieved to be 1−2/3α - (1 − x)2/3 = 0.7272 × e−38.29/8.314×T × t. The final stage of the experiment was carried out by characterizing the leached residues by X-ray diffractometer (XRD) and scanning electron microscopy (SEM), the result showed majorly the presence of rutile (TiO2), anglesite (PbSO4), and traces of iron-silicate face like pyrite (FeS), quartz (SiO2). Keywords: kinetics modelling, leaching, low-grade, recovery, shrinking core

Microstructure of In738Lc Fabricated Using Laser Powder Bed Fusion Additive Manufacturing

2021 ◽  
pp. 1-19
Author(s):  
Nandana Menon ◽  
Tanjheel Hasan Mahdi ◽  
Amrita Basak
Keyword(s):  
Additive Manufacturing ◽  
Electron Backscatter Diffraction ◽  
Small Scale ◽  
Second Phase ◽  
Face Centered Cubic ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Nickel Base Superalloys ◽  
Nickel Base

Abstract Nickel-base superalloys are extensively used in the production of gas turbine hot-section components as they offer exceptional creep strength and superior fatigue resistance at high temperatures. Such improved properties are due to the presence of precipitate-strengthening phases such as Ni3Ti or Ni3Al (gγ phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, the presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, specimens of IN738LC are fabricated on a Coherent Creator laser powder bed fusion (L-PBF) additive manufacturing (AM) equipment. Optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-Ray diffraction (XRD) are carried out to characterize the deposit region. Metallurgical continuity is achieved in the entire deposit region and the specimens do not show any warpage. However, the specimens show voids (e.g., pores and cracks) in the deposit region. The results show that the percentage void area decreases along the build height direction. The deposited IN738LC shows polycrystalline grains in the entire deposit region as confirmed by XRD and EBSD. The grain size also shows variations along the build direction. In summary, the results open opportunities for academic researchers and small scale businesses in fabricating high-gγ nickel-base superalloys on a desktop laser powder bed fusion AM equipment

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.

Quantification Of Pyrrhotiye O2 Consumption By Using Pyrite Oxidation Kinetic Data

2014 ◽  
Vol 1665 ◽  
pp. 93-101
Author(s):  
I. Rojo ◽  
F. Clarens ◽  
J. de Pablo ◽  
C Domènech ◽  
L. Duro ◽  
...  
Keyword(s):  
Experimental Data ◽  
Pyrite Oxidation ◽  
Oxidation Kinetic ◽  
Dissolution Kinetics ◽  
Buffering Capacity ◽  
Uptake Capacity ◽  
Kinetic Rate ◽  
Oxidation Rates ◽  
Redox Pair ◽  
Kinetics Of

ABSTRACTExperiments on the dissolution kinetics of natural pyrrhotite (FeS1-x-) and pyrite (FeS2) under imposed redox conditions to evaluate the oxygen uptake capacity of both minerals were carried out at 25°C and 1 bar. Experimental data indicate that in both cases, Fe(II) released from dissolution of these Fe-bearing sulphides is kinetically oxidized to Fe(III) to precipitate as Fe(III)-oxyhydroxides. While the system is pH controlled by the extent of the sulphide oxidation, Eh is controlled by the redox pair Fe2+/Fe(III)-oxyhydroxides. Pyrrhotite dissolution is faster than that of pyrite but generates less acidity. Consequently, the achieved redox value is more reducing. Experimental data show that the oxidation rates of both minerals (in mol·g-1·s-1) are equivalent under the studied conditions. This fact gives a new opportunity to quantify the reductive buffering capacity of pyrrhotite, for which no kinetic rate law has been still established.

scholarly journals Dissolution of Tunisian phosphate ore by a mixture of sulfuric and phosphoric acid: Kinetics study by means of differential reaction calorimetry

2019 ◽  
Vol 55 (1) ◽  
pp. 9-19
Author(s):  
Olfa Lachkar-Zamouri ◽  
Khemaies Brahim ◽  
Faten Bennour ◽  
Ismail Khattech
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Dissolution Rate ◽  
Dissolution Kinetics ◽  
Reaction Model ◽  
Reaction Calorimetry ◽  
Phosphate Ore ◽  
Differential Reaction ◽  
Apparent Activation Energies ◽  
Kinetics Of

A mixture of phosphoric and sulfuric acid was used to investigate the dissolution kinetics of phosphate ore by Differential Reaction Calorimetry (DRC). The effect of the solid-to-iquid ratio, concentration, stirring speed, particle size and temperature of the reaction is examined. It was established that the dissolution rate increased with stirring speed and particle size. However, rising the olid-to-iquid ratio, temperature and concentration decreased the dissolution rate. It was determined that the dissolution rate fits in the first order of the pseudo-homogeneous reaction model. Two negative values of apparent activation energies were found in the range of 25 to 60?C. The experimental data were tested by graphical and statistical methods and it was found that the following models were best fitted for the experimental data and an empirical equation for the process was developed. -ln (1 ? x) = [2,2 E-09((S/L)0.75C -0.461G0.447(SS) 0.471exp (2671/T)]t. T? 40?C -ln (1 ? x) = [2,2 E-09((S/L)0.75C -0.461G0.447(SS) 0.471exp (6959/T)]t. T > 45?C

Microstructure of IN738LC Fabricated Using Laser Powder Bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Nandana Menon ◽  
Tanjheel Hassan Mahdi ◽  
Amrita Basak
Keyword(s):  
Additive Manufacturing ◽  
Electron Backscatter Diffraction ◽  
Small Scale ◽  
Second Phase ◽  
Face Centered Cubic ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Nickel Base Superalloys ◽  
Nickel Base

Abstract Nickel-base superalloys are extensively used in the production of gas turbine hot-section components as they offer exceptional creep strength and superior fatigue resistance at high temperatures. Such improved properties are due to the presence of precipitate-strengthening phases such as Ni3Ti or Ni3Al (γ′ phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, the presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, specimens of IN738LC are fabricated on a Coherent Creator laser powder bed fusion (L-PBF) additive manufacturing (AM) equipment. Optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-Ray diffraction (XRD) are carried out to characterize the deposit region. Metallurgical continuity is achieved in the entire deposit region and the specimens do not show any warpage. However, the specimens show voids (e.g., pores and cracks) in the deposit region. The results show that the percentage void area decreases along the build height direction. The deposited IN738LC shows polycrystalline grains in the entire deposit region as confirmed by XRD and EBSD. The grain size also shows variations along the build direction. In summary, the results open opportunities for academic researchers and small-scale businesses in fabricating high-γ′ nickel-base superalloys on a desktop laser powder bed fusion AM equipment.

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