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STEM-EDS X-ray microanalysis of small precipitates in iron base thin foils
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
P. Doig , P. E. J. Flewitt
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
The experimental conditions for detection of segregated elements in the X-ray spectrum recorded from small precipitates ≦ 100 nm diameter contained within a thin foil of an iron base alloy using STEM-EDS X-ray microanalysis are described. The influence of precipitate size, position and composition, foil thickness, electron accelerating voltage, and X-ray emission intensity on its detectability are evaluated. Optimum experimental conditions for microanalysis of these precipitates are established and the limitations of current techniques discussed.
DOI : 10.1007/BF02662361
Anahtar Kelimeler : Metallurgical Transaction, Thin Foil, Electron Flux, Foil Thickness, Probe Size
ISSN: 1543-1940
Cilt: 14
Sayı: 10
Sayfa: 1943-1949
Sınıflandırma :
2
Development and application of growth models for grain boundary allotriomorphs of a stoichiometric compound in ternary systems
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Teiichi Ando , George Krauss
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
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Kaydet
A model for the isothermal growth of grain boundary allotriomorphs of a stoichiometric phase, (M, N)aIb, with a nonsingular interface in a ternary M-N-I matrix is developed. The element I is assumed to diffuse orders of magnitude faster than element N. The growth model assumes two initial no-partition growth stages and a subsequent partition growth stage with respect to element N. Both planar and spherical film geometries of allotriomorphs are considered. Strict mass balance conditions are taken into account so that the model can be used in rigorous computer simulations. A method to correct the allotriomorph thickness for the specific volume difference of the matrix and the precipitate is also shown. The growth of cementite allotriomorphs in Fe-Cr-C austenite is computer-simulated with the developed growth model. Interfacial concentration terms were calculated by programming the Sharma-Purdy-Kirkaldy regular solution model for the Fe-Cr-C system.
DOI : 10.1007/BF02664808
Anahtar Kelimeler : Austenite, Metallurgical Transaction, Cementite, Diffusion Field, Regular Solution Model
ISSN: 1543-1940
Cilt: 14
Sayı: 7
Sayfa: 1261-1269
Sınıflandırma :
3
Synthesis of in situ TiB 2 /TiN ceramic matrix composites from dense BN-Ti and BN-Ti-Ni powder blends
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
F. Olevsky , P. Mogilevsky , E. Y. Gutmanas , I. Gotman
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
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Kaydet
In the present research, near-net-shapein situ TiB2/TiN and TiB2/TiN/Ni composites were fabricated from cold-sintered BN/Ti and BN/Ti/Ni powder blends by pressureless displacement reaction synthesis or thermal explosion under pressure. In both approaches, the processing or preheating temperatures (≤1200 °C) were considerably lower than those typical of current methods used for the processing/consolidation of ceramic matrix composites. Microstructural characterization of the materials obtained was performed using X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Mechanical properties were evaluated by measuring microhardness, fracture toughness, and three-point bending strength. Application of a moderate external pressure (≤250 MPa) during self-propagating synthesis (SHS) synthesis was shown to be sufficient to ensure full density of the TiB2/TiN/Ni composite. The entire procedure of thermal explosion under pressure could be performed in open air without noticeable oxidation damage to the final product. The high fracture toughness of thein situ synthesized TiB2/TiN/Ni composite (20.5 MPa√m) indicated that the finely dispersed ductile Ni phase was effective in dissipating the energy of cracks propagating in the ceramic matrix.
DOI : 10.1007/BF02651860
Anahtar Kelimeler : Material Transaction, Thermal Explosion, Ceramic Matrix, Ni3Ti, Ceramic Matrix Composite
ISSN: 1543-1940
Cilt: 27
Sayı: 8
Sayfa: 2071-2079
Sınıflandırma :
4
Measurement of average grain volume and certain topological parameters by serial section analysis
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
F. N. Rhines , K. R. Craig , D. A. Rousse
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
Serial section analysis is suitable for the measurement of such topological parameters of a polycrystalline aggregate as number of grains, of grain faces, of grain edges and of grain corners in unit volume of the material. The number of grains in unit volume is of particular interest, because its reciprocal is the average grain volume, which is the only available shape-insensitive measure of grain size. An experimental approach to the serial section analysis of polycrystalline structures is developed.
DOI : 10.1007/BF02817891
Anahtar Kelimeler : Metallurgical Transaction, Serial Section, Topological Change, Topological Feature, Topological Parameter
ISSN: 1543-1940
Cilt: 7
Sayı: 11
Sayfa: 1729-1734
Sınıflandırma :
5
Interfacial Effect on the Deformation Mechanism of Bulk Nanolaminated Graphene-Al Composites
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Lei Zhao , Qiang Guo , Yan Shi , Yu Liu , Shmuel Osovski , Zhiqiang Li , Ding-Bang Xiong , Yishi Su , Di Zhang
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2019
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
Uniaxial tensile tests were carried on graphene (reduced graphene oxide, RGO)–Al laminated composites with Al lamella thicknesses varying from 1 μm down to 200 nm. It was found that there was a transition in plastic deformation mechanism, from a Hall–Petch-typed mechanism at 500 nm and 1 μm Al lamella thicknesses, to confined layer slip (CLS) of dislocations at the 200 nm Al lamella thickness. Moreover, the strengthening effect of RGO was only demonstrated in composite having 200-nm-thick Al lamellas, which can be rationalized by the enhanced barrier for dislocation de-pinning processes in the CLS mechanism.
DOI : 10.1007/s11661-018-05108-6
ISSN: 1543-1940
Cilt: 50
Sayı: 3
Sayfa: 1113-1118
Sınıflandırma :
6
Fatigue crack growth through alloyed niobium, Nb-Cr 2 Nb, and Nb-Nb 5 Si 3 in situ composites
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
David L. Davidson
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
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Kaydet
Fatigue cracks were grown through several niobium-based materials. For Nb-Cr-Ti composition materials, the single-phase alloy represented the matrix of two in situ composites with about 22 and 38 vol pct Cr2Nb. Grain boundaries were coated with intermetallic in the lower-volume fraction material, while the 38 vol pct Cr2Nb composite consisted of mainly spherical, dispersed intermetallic. The Nb-10Si composite was composed of about 28 vol pct primary Nb5Si3, with most of the matrix alloy in “fiberlike” shapes due to extrusion. Crack growth rates through the composites were generally faster than for unalloyed Nb, roughly in proportion to the volume fraction of intermetallic, although differences in microstructure make this comparison difficult. The presence of intermetallic greatly alters deformation of material near the crack tip. Particles of Cr2Nb were broken during the crack growth process, leading to increased crack growth rates. These results suggest microstructural modifications that could be expected to enhance fatigue crack growth resistance.
DOI : 10.1007/s11661-997-0266-4
Anahtar Kelimeler : Fracture Toughness, Material Transaction, Fatigue Crack, Crack Growth Rate, Fatigue Crack Growth
ISSN: 1543-1940
Cilt: 28
Sayı: 6
Sayfa: 1297-1314
Sınıflandırma :
7
Metric and Topological Characterization of the Advanced Stages of Loose Stack Sintering
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
A. S. Watwe , R. T. DeHoff
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
A quantitative stereological study, including serial sectioning analysis, has been carried out to determine the topological and metric properties of the pore and grain boundary networks in a series of samples prepared by loose stack sintering a 5-μm nickel powder at 1250 °C. The evolution of the structure is found to be determined by an interplay between the rates of three proceses: channel closure in the pore network, annihilation of isolated pores, and grain boundary migration. For the conditions of this study, this interplay produced a path characterized by isolation of pores from the starting network; these pores effectively pinned moving grain boundaries, arresting grain growth. The isolated pores, thus pinned in grain boundaries, then disappeared, so that at the end of the sequence, only network porosity remained. The traditional view that holds that isolated porosity is stable is thus found to be naive; a valid description of the geometry of the porosity cannot be obtained unambiguously without serial sectioning analysis.
DOI : 10.1007/BF02647214
Anahtar Kelimeler : Metallurgical Transaction, Microstructural Change, Pore Network, Boundary Migration, Sinter Time
ISSN: 1543-1940
Cilt: 21
Sayı: 11
Sayfa: 2935-2941
Sınıflandırma :
8
Modeling the mechanical behavior of tantalum
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Bing-Jean Lee , Kenneth S. Vecchio , Said Ahzi , Scott Schoenfeld
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
A crystal plasticity model is proposed to simulate the large plastic deformation and texture evolution in tantalum over a wide range of strain rates. In the model, a modification of the viscoplastic power law for slip and a Taylor interaction law for polycrystals are employed, which account for the effects of strain hardening, strain-rate hardening, and thermal softening. A series of uniaxial compression tests in tantalum at strain rates ranging from 10−3 to 104 s−1 were conducted and used to verify the model’s simulated stress-strain response. Initial and evolved deformation textures were also measured for comparison with predicted textures from the model. Applications of this crystal plasticity model are made to examine the effect of different initial crystallographic textures in tantalum subjected to uniaxial compression deformation or biaxial tensile deformation.
DOI : 10.1007/s11661-997-0087-5
Anahtar Kelimeler : Material Transaction, Tantalum, Slip System, Uniaxial Compression, True Strain
ISSN: 1543-1940
Cilt: 28
Sayı: 1
Sayfa: 113-122
Sınıflandırma :
9
The asymptotic theory of gasless combustion synthesis
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Stephen B. Margolis
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
The gasless, self-propagating, high-temperature synthesis of refractory materials is generally associated with a thin reaction zone that propagates through the material, converting the unburned reactant powders into a product alloy. The reactions themselves are characterized by large overall activation energies, a fact that can be exploited to derive asymptotic models in which the reaction zone becomes an infinitesimally thin sheet. Such models have been derived for both kinetically and diffusion-limited reactions, as well as for the intermediate case in which both chemical reaction and mass diffusion occur on comparable time scales. These models are amenable to analytical analysis, yielding formulas for the propagation speed of a steady, planar combustion wave and, in agreement with experiments, predicting critical parameter values above which stability is lost to one or more nonsteady modes of burning. In particular, nonlinear stability analyses have demonstrated the transition from steady to various periodic, quasi-periodic, and even chaotic combustion modes as a parameter related to the activation energy increases beyond the neutral stability threshold.
DOI : 10.1007/BF02660846
Anahtar Kelimeler : Shock Wave, Metallurgical Transaction, Combustion Wave, Jump Condition, Amplitude Equation
ISSN: 1543-1940
Cilt: 23
Sayı: 1
Sayfa: 15-22
Sınıflandırma :
10
Activation Enthalpies of Deformation-Induced Lattice Defects in Severe Plastic Deformation Nanometals Measured by Differential Scanning Calorimetry
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Daria Setman , Michael B. Kerber , Erhard Schafler , Michael J. Zehetbauer
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2009
Metallurgical and Materials Transactions A
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Kaydet
Samples of 99.99 pct pure copper and nickel of 99.998 pct purity were deformed by high-pressure torsion (HPT) at different hydrostatic pressures, to different shear strains. Activation enthalpies (Q) were determined by differential scanning calorimetry (DSC) using Kissinger’s method. For the one annealing peak found in HPT Cu, Q amounts to Q = 0.78 to 0.48 eV depending on the shear strain applied. In the case of Ni, the activation enthalpies of the two annealing peaks were determined as Q = 0.65 eV and Q = 0.95 eV, respectively, with no obvious dependence on shear strain, although this has been indicated by the annealing peak temperatures. Applying defect specific analyses of the annealing peaks, it turned out that the larger Q value represents the annihilation of dislocations and agglomerates, while the smaller one reflects the annihilation of single or double vacancies. Concerning the strain dependence of the larger Q, two possible explanations have been discussed: (1) the annihilation of dislocations assisted by the strain-dependent density of vacancy agglomerates and (2) the annihilation of dislocations enhanced by a strain-dependent level of long-range internal stresses. Because of closer correlations of Q with external and internal stresses at very high shear strains, explanation (2) has been favored.
DOI : 10.1007/s11661-009-0058-0
Anahtar Kelimeler : Differential Scanning Calorimetry, Shear Strain, Severe Plastic Deformation, Differential Scanning Calorimetry Measurement, High Pressure Torsion
ISSN: 1543-1940
Cilt: 41
Sayı: 4
Sayfa: 810-815
Sınıflandırma :
11
Surface Abrasive Torsion for Improved Mechanical Properties and Microstructure
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Ji Hyun Moon , Seung Mi Baek , Seok Gyu Lee , Jae Ik Yoon , Sunghak Lee , Hyoung Seop Kim
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2018
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
A novel process of discrete surface abrasion during simple torsion (ST), named “surface abrasive torsion (SAT),” is proposed to overcome the limitation of ST, i.e., insufficient strain for severe plastic deformation (SPD) due to cracks initiated on the surface, by removing the roughened surface region. The effect of SAT on delayed crack initiation was explained using finite element simulations. Larger shear deformation applicable to the specimen in SAT than ST was demonstrated experimentally.
DOI : 10.1007/s11661-018-4666-4
ISSN: 1543-1940
Cilt: 49
Sayı: 8
Sayfa: 3151-3156
Sınıflandırma :
12
Development of Strong η Fiber Recrystallization Texture in Rolled Fe 81 Ga 19 Thin Sheet
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Zhenghua He , Yuhui Sha , Fang Zhang , Feifei Lin , Liang Zuo
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2013
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
The 0.50-mm-thick Fe81Ga19 sheets were produced by rolling procedure, and texture evolution was investigated using macro- and microtexture analyses. The recrystallization texture dominated with strong η fiber (〈001〉//RD) was successfully obtained through sheet thickness by primary recrystallization annealing. The η fiber development can be attributed to the advantage in both grain number and grain size derived from the specially applied rolling process.
DOI : 10.1007/s11661-013-1832-6
Anahtar Kelimeler : Shear Band, Cold Rolling, Sheet Thickness, Rolling Process, Center Layer
ISSN: 1543-1940
Cilt: 45
Sayı: 1
Sayfa: 129-133
Sınıflandırma :
13
Mechanism of surface modification of the Ti-6Al-4V alloy using a gas tungsten arc heat source
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
M. Labudovic , R. Kovacevic , I. Kmecko , T. I. Khan , D. Blecic , Z. Blecic
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
The surface modification of a Ti-6Al-4V alloy using a gas tungsten arc, as a heat source, was studied. The experimental results show that the titanium alloy surface can be melted and nitrided using pure nitrogen or a nitrogen/argon mixture shielding atmosphere. The resolidified surfaces are 0.9 to 1.2-mm thick and contain titanium nitride dendrites, α-titanium, and α″-titanium (martensite). The average dendrite arm spacing is influenced by the electrode speed. Small titanium nitride dendrites are homogeneously distributed in the resolidified surfaces. The microstructure and phase constitution in the resolidified surfaces were determined and analyzed, and the mechanism of the formation of titanium nitrides is discussed. The results show that the nitriding kinetics obey parabolic laws and are, therefore, controlled by nitrogen diffusion. The nitrogen-concentration depth profiles, calculated using Fick’s second law of diffusion, are compared to experimental nitrogen depth profiles, showing satisfactory agreement.
DOI : 10.1007/s11661-999-0096-7
Anahtar Kelimeler : Martensite, Material Transaction, Surface Melting, Equilibrium Partial Pressure, Vanadium Nitride
ISSN: 1543-1940
Cilt: 30
Sayı: 6
Sayfa: 1597-1603
Sınıflandırma :
14
Effects of Wheel Surface Conditions on the Casting of Amorphous Metal Ribbons
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Shyh-Chin Huang , Howard C. Fiedler
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
The wetting of the liquid metal on the casting wheel surface is important in the continuous casting of amorphous metal ribbons. The wetting characteristics are substantially revealed by the wetting pattern on the wheel-side surface of the ribbon, which consists of areas of air pockets and areas of direct contact between metal and wheel. Experimental results will be presented regarding the effects of the condition of the casting wheel surface on the wetting pattern and the related interfacial phenomena such as the ribbon surface smoothness, the heat transfer at metal-wheel interface, and the separation of ribbon from the wheel. In particular, the mechanism of formation of the periodic ribbon surface defect known as “fish scale” and the elimination of this defect by changing the condition of the casting wheel surface will be discussed.
DOI : 10.1007/BF02643492
Anahtar Kelimeler : Matte Surface, Fish Scale, Wheel Surface, Interfacial Heat Transfer Coefficient, Ribbon Thickness
ISSN: 1543-1940
Cilt: 12
Sayı: 6
Sayfa: 1107-1112
Sınıflandırma :
15
Diffusion-Controlled Lengthening Rates of Bainitic Ferrite a Part of the Steel Genome
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Dergi Makalesi Open Access
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Lindsay Leach , John Ågren , Lars Höglund , Annika Borgenstam
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2019
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
As a step in the further development of models and databases to support design of new steels, i.e., the “steel genome”, the growth of bainitic ferrite plates is accounted for by a thermodynamic and kinetic approach. The thermodynamic aspects are represented by CALPHAD databases and a Gibbs energy barrier for growth Bm. Experimental information on ferrite-plate growth rates for a number of Fe-C alloys, some of high-purity, are analyzed in terms of a modified Zener–Hillert model and the barrier as well as some kinetic parameters are evaluated. It is found that the barrier varies in a smooth way with carbon content and lengthening rate. In order to improve the agreement with the experimental information it was necessary to adjust the diffusion coefficient of carbon in austenite at low temperatures. It is concluded that the representation of the experimental data is satisfactory.
DOI : 10.1007/s11661-019-05208-x
ISSN: 1543-1940
Cilt: 50
Sayı: 6
Sayfa: 2613-2618
Sınıflandırma :
16
Damage repair in CMSX-4 alloy without fatigue life reduction penalty
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Masakazu Okazaki , Issei Ohtera , Yoshio Harada
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
The microstructural changes in a single-crystal Ni-base superalloy, CMSX-4, that might occur during the processes of repair and recoating of hot section components for advanced gas turbines were studied. It is shown that the cellular γ/γ′ microstructure is formed when the material is subjected to local plastic straining, followed by the reheat treatments during the course of damage recovery. The formation of cellular microstructure in the material led to the remarkably reduced fatigue strength. In order to reduce or prevent the preceding undesirable effect resulting from cellular microstructure, a new method based on applying overlay coating technique was developed. The method is based on an idea that the alloying elements that are depleted in base alloys could be supplemented via the overlay coating. An X alloy, which contains grain boundary strengthening elements, was selected and coated on the CMSX-4 with the cellular microstructure by low-pressure plasma spraying. The fatigue tests on the coated CMSX-4 specimens demonstrated the effectiveness of the method. The observations of the crack initiation site, the fatigue fracture mode, the crack density in the cellular transformed area, and the crack propagation morphologies near the prior interface strongly supported the validity of this approach. The method is expected to build a road to a so-called damage cure (or recovery) coating.
DOI : 10.1007/s11661-004-0364-5
Anahtar Kelimeler : Fatigue, Material Transaction, Fatigue Life, Crack Density, Coated Specimen
ISSN: 1543-1940
Cilt: 35
Sayı: 2
Sayfa: 535-542
Sınıflandırma :
17
Accelerated Stress Corrosion Crack Initiation of Alloys 600 and 690 in Hydrogenated Supercritical Water
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Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Tyler Moss , Gary S. Was
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2017
Metallurgical and Materials Transactions A
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Kaydet
The objective of this study is to determine whether stress corrosion crack initiation of Alloys 600 and 690 occurs by the same mechanism in subcritical and supercritical water. Tensile bars of Alloys 690 and 600 were strained in constant extension rate tensile experiments in hydrogenated subcritical and supercritical water from 593 K to 723 K (320 °C to 450 °C), and the crack initiation behavior was characterized by high-resolution electron microscopy. Intergranular cracking was observed across the entire temperature range, and the morphology, structure, composition, and temperature dependence of initiated cracks in Alloy 690 were consistent between hydrogenated subcritical and supercritical water. Crack initiation of Alloy 600 followed an Arrhenius relationship and did not exhibit a discontinuity or change in slope after crossing the critical temperature. The measured activation energy was 121 ± 13 kJ/mol. Stress corrosion crack initiation in Alloy 690 was fit with a single activation energy of 92 ± 12 kJ/mol across the entire temperature range. Cracks were observed to propagate along grain boundaries adjacent to chromium-depleted metal, with Cr2O3 observed ahead of crack tips. All measures of the SCC behavior indicate that the mechanism for stress corrosion crack initiation of Alloy 600 and Alloy 690 is consistent between hydrogenated subcritical and supercritical water.
DOI : 10.1007/s11661-016-3898-4
Anahtar Kelimeler : Crack Initiation, Crack Growth Rate, Stress Corrosion Crack, Internal Oxidation, Chromium Carbide
ISSN: 1543-1940
Cilt: 48
Sayı: 4
Sayfa: 1613-1628
Sınıflandırma :
18
Effect of computational domain size on the mathematical modeling of transport processes and segregation during directional solidification
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
C. Frueh , D. R. Poirier , S. D. Felicelli
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
Using a finite-element simulator, a directionally solidified hypoeutectic Pb-Sn alloy was modeled in two dimensions to determine the effect of the height of the overlying liquid on convective transport and macrosegregation. It was determined that, while the strength of the convection in the overlying liquid depends on the square root of its height, one need not model the entire domain to predict freckling. Furthermore, the assumption of a constant thermal gradient in the liquid causes the predicted convection to be somewhat weaker than the convection in the temperature field used in directional solidification processing.
DOI : 10.1007/s11661-000-0092-4
Anahtar Kelimeler : Material Transaction, Domain Size, Mushy Zone, Constant Gradient, Thermosolutal Convection
ISSN: 1543-1940
Cilt: 31
Sayı: 12
Sayfa: 3129-3135
Sınıflandırma :
19
The structure of tempered martensite and its susceptibility to hydrogen stress cracking
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Bruce D. Craig , George Krauss
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
A series of 4130 steels modified with 0.50 pct Mo and 0.75 pct Mo were tempered at temperatures between 300 and 700 °C for one hour. The changes in the carbide dispersion and matrix substructure produced by tempering were measured by transmission electron microscopy. These measurements were correlated with resistance to hydrogen stress cracking produced by cathodic charging of specimens in three-point bending. Scanning electron microscopy showed that specimens tempered between 300 and 500 °C failed by intergranular cracking while those tempered at higher temperatures failed by a transgranular fracture mode. Auger electron spectroscopy showed that the intergranular fracture was associated with hydrogen interaction with P segregation and carbide formation at prior austenite grain boundaries. Transgranular cracking was initiated at inclusion particles from which cracks propagated to produce flat fracture zones extending over several prior austenite grains. The 4130 steels modified with higher Mo content resisted tempering and showed better hydrogen stress cracking resistance than did the unmodified 4130 steel. The transition in fracture mode is attributed to a decohesion mechanism in the low temperature tempered samples and a pressure mechanism in the highly tempered samples.
DOI : 10.1007/BF02655095
Anahtar Kelimeler : Carbide, Austenite, Metallurgical Transaction, Intergranular Fracture, Prior Austenite
ISSN: 1543-1940
Cilt: 11
Sayı: 11
Sayfa: 1799-1808
Sınıflandırma :
20
Thermodynamics-Based Computational Design of Al-Mg-Sc-Zr Alloys
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
G.N. Haidemenopoulos , A.I. Katsamas , H. Kamoutsi
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2010
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
Alloying additions of Sc and Zr raise the yield strength of Al-Mg alloys significantly. We have studied the effects of Sc and Zr on the grain refinement and recrystallization resistance of Al-Mg alloys with the aid of computational alloy thermodynamics. The grain refinement potential has been assessed by Scheil–Gulliver simulations of solidification paths, while the recrystallization resistance (Zener drag) has been assessed by calculation of the precipitation driving forces of the Al3Sc and Al3Zr intermetallics. Microstructural performance indices have been derived, used to rank several alloy composition variants, and finally select the variant with the best combination of grain refinement and recrystallization resistance. The method can be used, with certain limitations, for a thermodynamics-based design of Al-Mg and other alloy compositions.
DOI : 10.1007/s11661-009-0168-8
Anahtar Kelimeler : Al3Zr, Al3Sc, Heterogeneous Nucleation Site, Al3Zr Particle, Alloy Variant
ISSN: 1543-1940
Cilt: 41
Sayı: 4
Sayfa: 888-899
Sınıflandırma :
21
Foreword
Dergi Makalesi

Dergi Makalesi Open Access
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
A. K. Vasudevan , N. R. Moody , N. J. H. Holroyd , R. E. Ricker
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2012
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
DOI : 10.1007/s11661-012-1537-2
ISSN: 1543-1940
Cilt: 44
Sayı: 3
Sayfa: 1163-1163
Sınıflandırma :
22
Development of Wear-Resistant Cu-10Cr-3Ag Electrical Contacts with Nano-Al 2 O 3 Dispersion by Mechanical Alloying and High Pressure Sintering
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
S. Bera , W. Lojkowsky , I. Manna
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2009
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
Cu-10Cr-3Ag (wt pct) alloy with nanocrystalline Al2O3 dispersion was prepared by mechanical alloying and consolidated by high pressure sintering at different temperatures. Characterization by X-ray diffraction and scanning electron microscopy or transmission electron microscopy shows the formation of nanocrystalline matrix grains of about 40 nm after 25 hours of milling with nanometric (<20 nm) Al2O3 particles dispersed in it. After consolidation by high pressure sintering (8 GPa at 400 °C to 800 °C), the dispersoids retain their ultrafine size and uniform distribution, while the alloyed matrix undergoes significant grain growth. The hardness and wear resistance of the pellets increase significantly with the addition of nano-Al2O3 particles. The electrical conductivity of the pellets without and with nano-Al2O3 dispersion is about 30 pct IACS (international annealing copper standard) and 25 pct IACS, respectively. Thus, mechanical alloying followed by high pressure sintering seems a potential route for developing nano-Al2O3 dispersed Cu-Cr-Ag alloy for heavy duty electrical contact.
DOI : 10.1007/s11661-009-0019-7
Anahtar Kelimeler : Mechanical Alloy, Energy Dispersive Spectroscopy Analysis, Sintered Pellet, Wear Depth, International Annealing Copper Standard
ISSN: 1543-1940
Cilt: 40
Sayı: 13
Sayfa: 3276-3283
23
Discussion of “mechanism of steady-state grain growth in aluminum”
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
R. D. Doherty
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
DOI : 10.1007/BF02658421
Anahtar Kelimeler : Martensite, Metallurgical Transaction, DBTT, Ultimate Tensile Stress, Boundary Mobility
ISSN: 1543-1940
Cilt: 6
Sayı: 3
Sayfa: 588-590
Sınıflandırma :
24
G-phase formation in aged type 308 stainless steel
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
J. M. Vitek
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
DOI : 10.1007/BF02646233
Anahtar Kelimeler : Ferrite, Austenite, Metallurgical Transaction, Pearlite, Interlamellar Spacing
ISSN: 1543-1940
Cilt: 18
Sayı: 1
Sayfa: 154-156
Sınıflandırma :
25
High-temperature low-cycle fatigue behavior of a NIMONIC PE-16 superalloy—Correlation with deformation and fracture
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
M. Valsan , P. Parameswaran , K. Bhanu Sankara Rao , M. Vijayalakshmi , S.L. Mannan , D.H. Shastry
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
Low-cycle fatigue (LCF) responses of NIMONIC PE-16 for various prior microstructures and strain amplitudes have been evaluated and the fatigue behavior has been explained in terms of the operative deformation mechanisms. Total strain-controlled LCF tests were performed at 923 K on samples possessing three different prior microstructures: alloy A in solution-annealed condition (free of γ′ and carbides), alloy B with double aging treatment (spherical γ′ of 18-nm diameter and M23C6), and alloy C with another double aging treatment (γ′ of size 35 nm, MC and M23C6). All three microstructures exhibited an intial cyclic hardening followed by a period of gradual softening at 923 K. Coffin-Manson plots describing the plastic strain amplitudevs number of reversals to failure showed that alloy A had maximum fatigue life while C showed the least. Alloy B exhibited a two-slope behavior in the Coffin-Manson plot over the strain amplitudes investigated. This has been ascribed to the change in the degree of homogeneity of deformation at high and low strain amplitudes. Transmission electron microscopic studies were carried out to characterize the various deformation mechanisms and precipitation reactions occurring during fatigue testign. Fresh precipitation of fine γ′ was confirmed by the development of “mottled contrast” in alloy C. Evidence for the shearing of the ordered γ′ precipitates was revealed by the presence of superdislocations in alloy C. Repeated shearing during cyclic loading led to the reduction in the size of the γ′ and consequent softening. Coarser γ′ precipitates were associated with Orowan loops. The observed fatigue behavior has been rationalized based on the micromechanisms stated above and on the degree of homogenization of slip assessed by slipband spacing measurements on tested samples.
DOI : 10.1007/BF02804368
Anahtar Kelimeler : Fatigue Life, Strain Amplitude, Cyclic Softening, Plastic Strain Amplitude, Total Strain Amplitude
ISSN: 1543-1940
Cilt: 23
Sayı: 6
Sayfa: 1751-1761
Sınıflandırma :
26
Nucleation at larger supersaturations
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
Volker Ruth
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
In 1962, Lothe and Pound[4] modified the classical theory of homogeneous nucleation of Becker and Döring[3] by introducing free energy contributions which affected the predictions of nucleation rates and, consequently, the critical supersaturations required for the onset of condensation. As an approximation, Lothe and Pound added their energy contributions only to the classical formation energy of a critical nucleus. When the energy contributions are considered more rigorously for clusters of any size, the Lothe-Pound theory differs remarkably from its earlier approximations at larger supersaturations. Spontaneous condensation without nucleation is expected to occur at some critical large supersaturation. The condition for the onset of spontaneous condensation can be expressed in terms of a dimensionless energy parameter, γ, which also determines the nucleation rates. For a number of published condensation experiments, γ has been calculated. The evaluation reveals that the Lothe-Pound contributions can be justifiably neglected only in a few cases. In some other cases, spontaneous condensation is expected to occur.
DOI : 10.1007/BF02647535
Anahtar Kelimeler : Metallurgical Transaction, Supersaturation, Nucleation Rate, Critical Nucleus, Classical Nucleation Theory
ISSN: 1543-1940
Cilt: 23
Sayı: 7
Sayfa: 1853-1862
Sınıflandırma :
Fizik %75
27
The solidification characteristics of Fe-rich intermetallics in Al-11.5Si-0.4Mg cast alloys
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
X. Cao , J. Campbell
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
After the nucleation and sedimentation of primary Fe-rich phases, the microstructures of Al-11.5Si-0.4Mg cast alloys with 0.35–1.03Fe and 0.18–0.59Mn have been studied to investigate the solidification characteristics of Fe-rich phases. Depending on the iron and manganese contents as well as cooling rates, Fe-rich phases may solidify as predendritic (primary), pre-eutectic, coeutectic, and posteutectic intermetallics at the different stages of solidification through three types of reactions: (1) predendritic (primary), (2) eutectic, and (3) peritectic reactions. It seems that Fe-rich phases may nucleate on the wetted sides of double oxide films, while the gap of the dry sides of oxide films constitutes the cracks commonly observed in the Fe-rich phases and aluminum matrix. Conventional metallurgical observations also suggest that the Fe-rich phases nucleated early during the solidification might act as nuclei for those formed subsequently, although it has not been ruled out that these phases may share the same oxide substrates. It is probable that these nucleation events may all work as suggested in the possible nucleation hierarchy for Al-11.5Si-0.4Mg cast alloys.
DOI : 10.1007/s11661-004-0251-0
Anahtar Kelimeler : Material Transaction, Oxide Film, Cast Alloy, Secondary Electron Image, Chinese Script
ISSN: 1543-1940
Cilt: 35
Sayı: 5
Sayfa: 1425-1435
Sınıflandırma :
28
Occurrence and Morphology of Martensite in β -Cu-Zn Alloys with Minor Al Additions
Dergi Makalesi

Dergi Makalesi Open Access
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
T. Kaaden , P. Wutzler , S. Lippmann
Konu :
etallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2020
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
The limits of occurrence and the morphology of martensite in Cu-Zn-Al alloys with 30 to 50 wt pct Zn and ≤ 1.5 wt pct Al have been investigated. In samples with concentration gradients, various conditions for the competition between martensitic and massive transformation have been observed. Microstructural details of martensite were obtained by combining vibration polishing, chemical or plasma etching and polarized light, backscattered electron channeling contrast or electron backscatter diffraction analysis. Depending on the cooling rate, martensite undergoes a morphological change from self-accommodating thin plates to lenticular shaped plates, which is documented for the first time in Cu-based alloys. The number of martensite twins in the investigated compositional range was found to be significantly smaller than that in commercial Cu-Zn-Al alloys that are used as shape memory alloys.
DOI : 10.1007/s11661-020-05769-2
ISSN: 1543-1940
Cilt: 51
Sayı: 7
Sayfa: 3403-3409
Sınıflandırma :
29
Delta ferritic heat-resistant chromium-molybdenum steels with improved rupture strength
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
P. J. Grobner , V. Bišs , D. L. Sponseller
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
Nine experimental delta-ferritic steels have been examined as potential low expansion heat-resistant steels for use in fossil fuel power generation, nuclear power generation, nuclear process heat plants and coal gasification plants. The steels contain 10 to 14 pct Cr and 2 to 6 pct Mo, with additions of columbium, titanium, vanadium, aluminum and boron. Room-temperature tensile properties and oxidation resistance of all steels were determined. Selected steels were aged for 1000 h at 760 °C (1400 °F) and subjected to elevated temperature tensile tests at the aging temperature. Creep-rupture properties of selected steels were determined at 760 and 815 °C (1400 and 1500 °F). Extensive metallographic and phase identification studies were conducted. Of the two steels tested for creep-rupture strength, the 10Cr-6Mo-0.5Cb steel, with good room-temperature ductility, has rupture strength exceeding that of martensitic 12Cr-1Mo-V steel. The 14Cr-3Mo-0.5Cb-lTi-2Al steel exhibits an even higher rupture strength, but has only marginal ductility at room temperature.
DOI : 10.1007/BF02654704
Anahtar Kelimeler : Lave Phase, Rupture Strength, High Silicon Content, Columbium, Heat Resistant Steel
ISSN: 1543-1940
Cilt: 11
Sayı: 6
Sayfa: 909-917
Sınıflandırma :
30
Effect of Friction Stir Processing Procedures on Microstructure and Mechanical Properties of Mg-Al-Zn Casting
Dergi Makalesi

Dergi Makalesi
Kaynak :
Springer Link
Yayıncı :
Metallurgical and Materials Transactions A
Yazar(lar) :
A. H. Feng , B. L. Xiao , Z. Y. Ma , R. S. Chen
Konu :
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl :
2009
Metallurgical and Materials Transactions A
Yayıncı Web Sitesi Tam Metin
Kaydet
Cast Mg-Al-Zn (AZ80) alloy was subjected to friction stir processing (FSP) with three different FSP procedures: single pass, single pass with a pre–solution treatment (pre-ST), and two pass. FSP resulted in remarkable grain refinement, significant breakup, and dissolution of the coarse, networklike Mg17Al12 phase. While the single-pass FSP procedure produced a heterogeneous microstructure with Mg17Al12 particle-rich bands, both the pre-ST FSP and the two-pass FSP procedures resulted in the generation of a uniform microstructure. The pre-ST FSP and two-pass FSP samples exhibited significantly enhanced strength and ductility due to remarkable grain refinement and dissolution of coarse Mg17Al12 phase. A post-FSP aging resulted in the precipitation of fine Mg17Al12 particle, thereby increasing the strength of the FSP samples. Among three FSP samples, the aged two-pass FSP sample exhibited the highest ultimate tensile strength (UTS) of 356 MPa and an elongation of 17 pct.
DOI : 10.1007/s11661-009-9923-0
Anahtar Kelimeler : Friction Stir Processing, Stir Zone, Discontinuous Precipitation, Crystal Lattice Parameter, Magnesium Matrix
ISSN: 1543-1940
Cilt: 40
Sayı: 10
Sayfa: 2447-2456
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