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Materials Challenges for Advanced Combustion and Gasification Fossil Energy Systems
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Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
S. Sridhar , P. Rozzelle , B. Morreale , D. Alman
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl:
2011
Materials Challenges for Advanced Combustion and Gasification Fossil Energy Systems This special section of Metallurgical and Materials Transactions is devoted to materials challenges associated with coal based energy conversion systems Affordable materials that can meet the demanding performance requirements will be a key enabling technology for these systems.
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This special section of Metallurgical and Materials Transactions is devoted to materials challenges associated with coal based energy conversion systems. The purpose of this introductory article is to provide a brief outline to the challenges associated with advanced combustion and advanced gasification, which has the potential of providing clean, affordable electricity by improving process efficiency and implementing carbon capture and sequestration. Affordable materials that can meet the demanding performance requirements will be a key enabling technology for these systems.
DOI: 10.1007/s11661-011-0627-x
Anahtar Kelimeler: Flyash, Gasification, Syngas, Oxide Scale, Steam Temperature
ISSN: 1543-1940
Cilt: 42
Sayı: 4
Sayfa: 871-877
Sınıflandırma:
2
Discussion of Six Papers From May 2013 Issue
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
John Campbell
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl:
2013
The May 2013 issue of Metallurgical and Materials Transactions A is a typical issue, containing a number of papers, all of which would be explicable assuming
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The May 2013 issue of Metallurgical and Materials Transactions A is a typical issue, containing a number of papers, all of which would be explicable assuming the near-universality of the presence of oxide bifilms in metals as a result of the entrainment of the surface oxide film during pouring. The unbonded interface between the necessarily doubled-over surface film, often only a few nanometers thick, and often occurring at grain boundaries, appears to be the cause of grain boundary failures and the initiation of cracks. The precipitation of second phases on the outer surfaces of the bifilm, in good atomic contact with the matrix, explains the apparent brittleness of many intermetallics and second phases. The number of papers from the May issue of MMTA illustrates the ubiquitous presence of bifilms, up to now almost unknown, and their central importance in physical metallurgy, and their possible control, in turn, by up-to-date process metallurgy.
DOI: 10.1007/s11661-013-1857-x
Anahtar Kelimeler: Thermomechanical Fatigue, Rolling Contact Fatigue, Ductile Dimple, Compact Graphite, Hadfield Steel
ISSN: 1543-1940
Cilt: 44
Sayı: 10
Sayfa: 4466-4468
Sınıflandırma:
3
A review of positron studies of the annealing of the cold worked state
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
J. G. Byrne
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
For the most part the examples will not reveal new metallurgical factsper se, but rather will serve to introduce the metallurgist or materials specialist include ones from conventional cold rolling and annealing, oriented single crystal bending and subsequent polygonization, fatigue of ferrous and nonferrous materials
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This review will present examples of the application of positron annihilation to studies of cold work and annealing. For the most part the examples will not reveal new metallurgical factsper se, but rather will serve to introduce the metallurgist or materials specialist to a relatively new and possibly advantageous type of measurement which he (or she) may wish to apply to particular studies. The examples cited include ones from conventional cold rolling and annealing, oriented single crystal bending and subsequent polygonization, fatigue of ferrous and nonferrous materials, tensile work hardening of various grain size samples, electron radiation and annealing, shot peening, age hardening retardation by cold work and influence of the cold worked state upon hydrogen charging. The reader is referred to the preceeding article by Dr. K. G. Lynn for a more detailed explanation of the two positron techniques utilized in gathering the results described, namely positron lifetime measurements and Doppler broadening of the positron annihilation gamma ray energies. The author is indebted to the many former and current students and research associates whose work is to be described and who will be cited in the text at the appropriate times.
DOI: 10.1007/BF02658297
Anahtar Kelimeler: Positron Lifetime, Cold Rolled Copper
ISSN: 1543-1940
Cilt: 10
Sayı: 7
Sayfa: 791-807
Sınıflandırma:
4
Development of Processing Maps for Hot Deformation: Algorithm and Common Errors
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
N. Neethu , P. Chakravarthy
Konu:
etallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl:
2020
The development of processing maps using the dynamic materials modeling (DMM) approach is a widely used method for choosing the appropriate process parameters This paper highlights the correct algorithm for developing the processing map by calculating the metallurgical power dissipation efficiency (η) and the
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The development of processing maps using the dynamic materials modeling (DMM) approach is a widely used method for choosing the appropriate process parameters for the thermomechanical processing of any material. This paper highlights the correct algorithm for developing the processing map by calculating the metallurgical power dissipation efficiency (η) and the newly proposed binary instability parameter (β). Further, common errors that can arise during the computations, and their consequences are also highlighted.
DOI: 10.1007/s11661-020-05817-x
ISSN: 1543-1940
Cilt: 51
Sayı: 7
Sayfa: 3398-3402
Sınıflandırma:
5
Mechanism of resistance microwelding of crossed fine nickel wires
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
S. Fukumoto , Y. Zhou
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
mechanisms, in which the effects of main process parameters (welding current and force and weld time) were investigated by detailed mechanical testing and metallurgical
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Resistance microwelding of fine crossed nickel wires is of increasing industrial importance for electrical connections in downsized electronic and medical devices, but the understanding of the process is very limited. A study has, therefore, been performed to clarify the basic joining mechanisms, in which the effects of main process parameters (welding current and force and weld time) were investigated by detailed mechanical testing and metallurgical examinations. A bonding mechanism with main process stages (wire cold collapse, surface melting, molten-phase squeeze-out and, solid-state bonding) was proposed. A new technique has also been developed to optimize the process by initiating the welding current well before the electrode force has reached its full nominal value.
DOI: 10.1007/s11661-004-0061-4
Anahtar Kelimeler: Welding, Material Transaction, Bond Interface, Welding Current, Joint Strength
ISSN: 1543-1940
Cilt: 35
Sayı: 10
Sayfa: 3165-3176
Sınıflandırma:
6
Creep-rupture in powder metallurgical nickel-base superalloys at intermediate temperatures
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
C. C. Law , M. J. Blackburn
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Creep-rupture in powder metallurgical nickel-base superalloys at intermediate temperatures To gain insight into the factors which control the creep-rupture properties of powder metallurgical nickel-base superalloys at intermediate temperatures Metallurgical Transaction
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To gain insight into the factors which control the creep-rupture properties of powder metallurgical nickel-base superalloys at intermediate temperatures (650 to 775°C), a comparative study was conducted on the alloys AF115, modified MAR-M432 (B6) and modified IN100 (MERL76). Creep-rupture properties in these alloys were characterized in terms of the stress and temperature dependence of the secondary creep rate, εS, andrupture time,t R . Within the limited stress ranges used, the stress dependence of both εS andt R at 704°C can be represented by power laws εS andC n andt R =Mσ -p ; whereC,M, n, andp are constants. The stress exponentsn andp are approximately equal for both AF115 and B6 with values of 16 and 7, respectively. In the case of MERL76,n andp are different, with values of 15 and 5, respectively. The apparent activation energies,Q, are 700, 370 and 520 KJ mol-1 for AF115, B6 and MERL76, respectively. For these alloys, long creep-rupture lives are associated with large values ofn andQ. The sig-nificant differences inn andQ values between AF115 and B6 were related to creep re-covery processes for which the lattice misfit between the gamma and the gamma prime was identified to be an important parameter. However, the unequaln andp values in MERL76 compared with those in AF115 and B6, were traced to differences in fracture mode. Failures in AF115 and B6 were initiated at carbide particles at grain boundaries. In contrast, fracture in MERL76 was initiated at grain boundary triple junctions. The rupture lives of AF115 and B6 can be modeled reasonably well by the growth of cavities during secondary creep and propagation of a surface-nucleated crack during the tertiary creep.
DOI: 10.1007/BF02654573
Anahtar Kelimeler: Metallurgical Transaction, Crack Growth Rate, Rupture Life, Rupture Time, Creep Crack Growth
ISSN: 1543-1940
Cilt: 11
Sayı: 3
Sayfa: 495-507
Sınıflandırma:
7
The shape of things past and to come
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
Monty Finniston
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
The historical development of metallurgy and of engineering materials establishes the importance of culture and economy on the guidance of progress and indication of revolutionary scientific changes in our understanding and hence control of metals in the near future, but significant alteration of industrial metallurgical procedures must occur as required by political considerations and availability of raw materials including fuels.
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The historical development of metallurgy and of engineering materials establishes the importance of culture and economy on the guidance of progress and change. There is no indication of revolutionary scientific changes in our understanding and hence control of metals in the near future, but significant alteration of industrial metallurgical procedures must occur as required by political considerations and availability of raw materials including fuels.
DOI: 10.1007/BF02652241
ISSN: 1543-1940
Cilt: 9
Sayı: 9
Sayfa: 1177-1186
8
Effects of silicon additions and retained austenite on stress corrosion cracking in ultrahigh strength steels
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
Robert O. Ritchie , M. H. Castro Cedeno , V. F. Zackay , E. R. Parker
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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A study has been made of the effects of silicon additions and of retained austenite on the stress-corrosion cracking (SCC) behavior of commercial ultrahigh strength steels (AISI 4340 and 300-M) tested in aqueous solutions. By comparing quenched and tempered structures of 4340 and 300-M i) at equivalent strength and ii) at their respective optimum and commercially-used heat-treated conditions, the beneficial role of silicon addition on SCC re-sistance is seen in decreased Region II growth rates, with no change in K’ISCC. The beneficial role of retained austenite is demonstrated by comparing isothermally transformed 300-M, containing 12 pct austenite, with conventionally quenched and tempered structures of 300-M and 4340, containing less than 2 pct austenite, at identical yield strength levels. Here, the isothermally transformed structure shows an order of magnitude lower Region II SCC growth rates than quenched and tempered 300-M and nearly two orders of magnitude lower Region II growth rates than 4340, K ISCC values remaining largely unchanged. The results are discussed in terms of hydrogen embrittlement mechanisms for SCC in martensitic high strength steels in the light of the individual roles of hydrogen diffusivity and carbide type.
DOI: 10.1007/BF02647168
Anahtar Kelimeler: Austenite, Metallurgical Transaction, Cementite, Bainite, Lower Bainite
ISSN: 1543-1940
Cilt: 9
Sayı: 1
Sayfa: 35-40
Sınıflandırma:
9
An experimental and theoretical study of cementite dissolution in an Fe-Cr-C alloy
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
ZI-Kui Liu , Lars Höglund , Björn Jönsson , John ågren
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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The dissolution of cementite at 910 °C in an Fe-2.06Cr-3.91C (at. pct) alloy is investigated experimentally. The Cr concentration profiles in austenite and cementite are measured by means of the scanning transmission electron microscopy/energy dispersive spectrometry (STEM/EDS) technique at different dissolution times. The measurements show the Cr enrichment in the cementite during the dissolution process. The measurements suggest that the main part of the reaction for this alloy is controlled by Cr diffusion in the cementite or in the austenite matrix. This observation is in agreement with predictions of the local equilibrium hypothesis. The carbide fraction and average particle diameter are evaluated as functions of dissolution time. The Cr enrichment of the cementite results in a supersaturation and a possible decomposition of the cementite. Microstructural evidence for such a decomposition is found by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A new program package called DICTRA,[11] which is suitable for the simulation of diffusional reactions in multicomponent alloys, has been applied to the present case. The simulation is compared with the experimental data, and a good agreement between the two is found.
DOI: 10.1007/BF02646498
Anahtar Kelimeler: Ferrite, Austenite, Metallurgical Transaction, Cementite, Chromium Content
ISSN: 1543-1940
Cilt: 22
Sayı: 8
Sayfa: 1745-1752
Sınıflandırma:
10
Tempering of Mn and Mn-Si-V dual-phase steels
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
G. R. Speich , A. J. Schwoeble , G. P. Huffman
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Changes in the yield behavior, strength, and ductility of a Mn and a Mn-Si-V d11Al-phase (ferrite-martensite) steel were investigated after tempering one hour at 200 to 600 °C. The change in yield behavior was complex in both steels with the yield strength first increasing and then decreasing as the tempering temperature was increased. This complex behavior is attributed to a combination of factors including carbon segregation to dislocations, a return of discontinuous yielding, and the relief of resid11Al stresses. In contrast, the tensile strength decreased continuously as the tempering temperature was increased in a manner that could be predicted from the change in hardness of the martensite phase using a simple composite strengthening model. The initial tensile ductility (total elongation) of the Mn-Si-V steel was much greater than that of the Mn steel. However, upon tempering up to 400 °C, the ductility of the Mn-Si-V decreased whereas that of the Mn steel increased. As a result, both steels had similar ductilities after tempering at 400 °C or higher temperatures. These results are attributed to the larger amounts of retained austenite in the Mn-Si-V steel (9 pct) compared to the Mn steel (3 pct) and its contribution to tensile ductility by transforming to martensite during plastic straining. Upon tempering at 400 °C, the retained austenite decomposes to bainite and its contribution to tensile ductility is eliminated.
DOI: 10.1007/BF02670446
Anahtar Kelimeler: Ferrite, Austenite, Tensile Strength, Martensite, Metallurgical Transaction
ISSN: 1543-1940
Cilt: 14
Sayı: 6
Sayfa: 1079-1087
Sınıflandırma:
11
Metallurgical problems and opportunities in coal-fired steam power plants
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
R. I. Jaffee
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical problems and opportunities in coal-fired steam power plants External constraints on the generation of electricity in steam power plants that determine metallurgical research and development include 1) the source Environmental constraints on SO2 emission dominate a great deal of current materials research and development. The main current effort in materials research and development is aimed at improved reliability rather than efficiency.
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External constraints on the generation of electricity in steam power plants that determine metallurgical research and development include 1) the source of fuel, 2) environmental controls, 3) the economy of scale, 4) efficiency of energy conversion, and 5) reliability of the power generating equipment. These are reviewed in the current time frame. Economic and political factors dictate that coal and nuclear fission are the major fuels for generation of electricity until the end of the century. Environmental constraints on SO2 emission dominate a great deal of current materials research and development. Only a small percentage of available coal is low enough in sulfur to meet new source standards. Conversion of coal to a clean gaseous, liquid, or solid fuel is replete with difficult metallurgical problems, chiefly in high temperature corrosion. To compete with stack gas desulfurization it is necessary to burn the clean converted coal in more thermally efficient combined cycles, which requires development of high temperature industrial gas turbines. The fabrication problems of advanced air or water cooling of metal hot components are traded off against the brittle design problems of ceramic components. Removal of sulfur in the combustion stage in fluidized beds containing an SO2 acceptor has many attractive features, but potential problems exist in hot corrosion of the in-bed tubes and erosioncorrosion-fouling of expander turbines. The economy of scale has increased power plant size to about 1200 MW, where further increases seem to have stalled because of metallurgical problems. Improvements in thermal efficiency from high steam temperatures and pressures also have stalled, and even retreated, because of metallurgical barriers. The main current effort in materials research and development is aimed at improved reliability rather than efficiency. Two metallurgical opportunities to improve reliability are described in detail: titanium low pressure turbine blades and large rotor forgings.
DOI: 10.1007/BF02817624
ISSN: 1543-1940
Cilt: 10
Sayı: 2
Sayfa: 139-164
Sınıflandırma:
12
Metallurgical processing, structure and superconducting transition temperature of V 3 Ga
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
B. N. Das , J. E. Cox , R. W. Huber , R. A. Meussner
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical processing, structure and superconducting transition temperature of V 3 Ga Alloy compositions, spanning the A15 phase field and the adjacent two phase fields, were arc melted and cast as rods for the study of metallurgical processing In cast materials, dendritic segregation was observed by metallographic examination and a radial Ga gradient was revealed by inductive super conducting Metallurgical Transaction
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Alloy compositions, spanning the A15 phase field and the adjacent two phase fields, were arc melted and cast as rods for the study of metallurgical processing, resultant microstructures and superconductivity of V3Ga. In cast materials, dendritic segregation was observed by metallographic examination and a radial Ga gradient was revealed by inductive super conducting transition temperature measurement. A brief heat treatment at temperatures in the bcc-phase field eliminated the dendritic segregation, decreased the radial Ga gradient, and produced very similar microstructures in the full range of compositions. The fine scale segregation generated in the bcc-to-A15 transformation was removed by an anneal at 1000 to 1150°C. The series of annealed specimens were uniform in microstructure and also in hardness. The lattice parameter-composition plot defined two lines intersecting near the stoichiometric composition. These data and density measurements show that the compositional adjustment is by substitution of V and Ga atoms on lattice sites. The superconducting transition temperature drops rapidly from a maximum as the composition deviates from stoichiometry. Measured values of the zero field transition temperature are somewhat higher than theT o determined by extrapolating low fieldT c measurements to zero field.
DOI: 10.1007/BF02676975
Anahtar Kelimeler: Metallurgical Transaction, Superconducting Transition Temperature, Annealed Specimen, Dendritic Segregation, Radial Segregation
ISSN: 1543-1940
Cilt: 8
Sayı: 4
Sayfa: 541-552
Sınıflandırma:
13
Microstructure and local brittle zone phenomena in high-strength low-alloy steel welds
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
B. C. Kim , S. Lee , N. J. Kim , D. Y. Lee
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl:
2012
The LBZ in the HAZ of a mUltipass welded joint is the intercritically reheated coarse-grained HAZ whose properties are strongly influenced by metallurgical Metallurgical Transaction
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This study is concerned with a correlation between the microstructure and the local brittle zone (LBZ) phenomena in high-strength low-alloy (HSLA) steel welds. The influence of the LBZ on toughness was investigated by means of simulated heat-affected zone (HAZ) tests as well as welded joint tests. Micromechanical processes involved in microvoid and cleavage microcrack formation were also identified using notched round tensile tests and subsequent scanning electron microscopy (SEM) analyses. The LBZ in the HAZ of a mUltipass welded joint is the intercritically reheated coarse-grained HAZ whose properties are strongly influenced by metallurgical factors such as an effective grain size and high-carbon martensitic islands: The experimental results indicated that Charpy energy was found to decrease monotonically with increasing the amount of martensitic islands, confirming that the martensitic island is the major microstructural factor controlling the HAZ toughness. In addition, microvoids and microcracks were found to initiate at the interface between the martensitic island and the ferrite matrix, thereby causing the reduction in toughness. These findings suggest that the LBZ phenomena in the coarse-grained HAZ can be explained by the morphology and the amount of martensitic islands.
DOI: 10.1007/BF03350956
Anahtar Kelimeler: Martensite, Metallurgical Transaction, Bainite, Post Weld Heat Treatment, Cleavage Fracture
ISSN: 1543-1940
Cilt: 22
Sayı: 1
Sayfa: 139-149
Sınıflandırma:
14
Development of Ultrafine-Grained Dual-Phase Steels: Mechanism of Grain Refinement During Intercritical Deformation
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
Anish Karmakar , R. D. K. Misra , S. Neogy , Debalay Chakrabarti
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl:
2013
However, the sequence of those metallurgical events and the temperature range over which any particular mechanism dominates is not yet well understood.
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Heavy deformation of metastable austenite (below Ae3) or both austenite and ferrite in the two-phase region (between Ar3 and Ar1) is known to develop an ultrafine ferrite grain structure with an average grain size of less than 3 μm. Different dynamic softening mechanisms, such as dynamic recovery, dynamic recrystallization, and dynamic strain-induced austenite→ferrite transformation (DSIT), are responsible for such grain refinement. However, the sequence of those metallurgical events and the temperature range over which any particular mechanism dominates is not yet well understood. The current study throws some light on this aspect by applying heavy, single-pass compressive deformation (with true strain of 1.0) on the microalloyed steel samples over a temperature range of 1173 K to 873 K (900 °C to 600 °C) using a Gleeble simulator (Dynamic Systems Inc., Poestenkill, NY) and water quenching the samples immediately after deformation. The current study showed the dominating effect of the following mechanisms with respect to the deformation temperature: (1) DSIT followed by conventional dynamic recrystallization (Conv-DRX) of ferrite at higher deformation temperatures (≥1073 K [800 °C]), (2) extended recovery and continuous dynamic recrystallization (Cont-DRX) of ferrite at intermediate deformation temperatures (~1023 K [750 °C]), and (3) simple dynamic recovery of ferrite at lower deformation temperatures (≤923 K [650 °C]).
DOI: 10.1007/s11661-013-1757-0
Anahtar Kelimeler: Ferrite, Austenite, Dynamic Recrystallization, Texture Component, Dynamic Recovery
ISSN: 1543-1940
Cilt: 44
Sayı: 9
Sayfa: 4106-4118
Sınıflandırma:
15
Improved ductility of Ni 3 Si by microalloying with boron or carbon
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
A. I. Taub , C. L. Briant
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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The effects of boron and carbon additions on the tendency for intergranular fracture in trinickel silicide intermetallics are reported. Melt spinning of Ni77Si23 alloyed with 0.1 at. pet boron results in full bend ductility and complete transgranular fracture compared with brittle intergranular fracture for the unmodified compound. Alloying with 0.1 at. pet carbon also produces full bend ductility but a mixed mode failure (≈30 pct transgranular). For both carbon and boron additions, reducing the Ni concentration of the base compound results in a greater percentage of intergranular fracture. The boron solubility limit depends on the Ni concentration of the base compound. For Ni77Si23, the solubility limit is between 0.1 and 0.2 at. pet boron. For compounds with silicon concentrations of 23.5 and 24.0 at. pct, the solubility limit is less than 0.1 at. pct boron. Boron additions above the solubility limit result in Ni3B precipitates which degrade the bend ductility and increase the percentage of integranular fracture. Alloying with carbon above the solubility limit (<0.1 at. pct) produces graphite precipitation. For Ni77Si23, increasing the carbon concentration from 0.1 to 1.0 at. pct resulted in no change in the ductility. Auger examination of the grain boundary composition showed strong segregation of both boron and carbon. Enrichment in silicon concentration was also observed.
DOI: 10.1007/BF02650289
Anahtar Kelimeler: Boron, Ductility, Metallurgical Transaction, Intergranular Fracture, Boron Concentration
ISSN: 1543-1940
Cilt: 20
Sayı: 10
Sayfa: 2025-2032
16
Mechanisms of tempered martensite embrittlement in low alloy steels
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
R. M. Horn , Robert O. Ritchie
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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An investigation into the mechanisms of tempered martensite embrittlement (TME), also know as “500°F” or “350°C” or one-step temper embrittlement, has been made in commercial, ultra-high strength 4340 and Si-modified 4340 (300-M) alloy steels, with particular focus given to the role of interlath films of retained austenite. Studies were performed on the variation of i) strength and toughness, and ii) the morphology, volume fraction and thermal and mechanical stability of retained austenite, as a function of tempering temperature, following oil-quenching, isothermal holding, and continuous air cooling from the austenitizing temperature. TME was observed as a decrease in bothK Ic and Charpy V-notch impact energy after tempering around 300°C in 4340 and 425°C in 300-M, where the mechanisms of fracture were either interlath cleavage or largely transgranular cleavage. The embrittlement was found to be concurrent with the interlath precipitation of cementite during temperingand the consequent mechanical instability of interlath films of retained austenite during subsequent loading. The role of silicon in 300-M was seen to retard these processes and hence retard TME to higher tempering temperatures than for 4340. The magnitude of the embrittlement was found to be significantly greater in microstructures containing increasing volume fractions of retained austenite. Specifically, in 300-M the decrease inK Ic, due to TME, was a 5 MPa√m in oil quenched structures with less than 4 pct austenite, compared to a massive decrease of 70 MPa√m in slowly (air) cooled structures containing 25 pct austenite. A complete mechanism of tempered martensite embrittlement is proposed involving i) precipitation of interlath cementite due to partial thermal decomposition of interlath films of retained austenite, and ii) subsequent deformation-induced transformation on loading of remaining interlath austenite, destabilized by carbon depletion from carbide precipitation. The deterioration in toughness, associated with TME, is therefore ascribed to the embrittling effect of i) interlath cementite precipitates and ii) an interlath layer of mechanically-transformed austenite,i.e., untempered martensite. The presence of residual impurity elements in prior austenite grain boundaries, having segregated there during austenitization, may accentuate this process by providing an alternative weak path for fracture. The relative importance of these effects is discussed.
DOI: 10.1007/BF02652208
Anahtar Kelimeler: Austenite, Metallurgical Transaction, Cementite, Lath Boundary, Ductile Rupture
ISSN: 1543-1940
Cilt: 9
Sayı: 8
Sayfa: 1039-1053
Sınıflandırma:
17
Niobium carbonitride precipitation and austenite recrystallization in hot-rolled microalloyed steels
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
S. S. Hansen , J.B. Vander Sande , Morris Cohen
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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The response of austenites to thermomechanical treatments is studied in a series of niobium (columbium) HSLA steels. Interactions between composition, plastic deformation, strain-induced precipitation, and austenite recrystallization are described and related to previous work in the field. Niobium in solution prior to deformation leads to significant retardation of subsequent austenite recrystallization if Nb(C,N) precipitation takes place prior to or during the early stages of recrystallization. Such straininduced precipitation proceeds in two stages: initially at austenitic grain boundaries and deformation bands, and later on substructural features in the unrecrystallized austenite. The latter precipitation is accelerated only if it occurs in the unrecrystallized austenite; if recrystallization precedes Nb(C,N) precipitation, then the precipitation reaction is much slower. Thus, the Nb(C,N) precipitation and austenite recrystallization reactions are coupled phenomena. The conditions necessary for such an interaction are analyzed, and it is proposed that the level of supersaturation of Nb(C,N) in the austenite at the deformation temperature is a critical factor in determining whether or not an effective interaction will operate at that temperature.
DOI: 10.1007/BF02654563
Anahtar Kelimeler: Austenite, Metallurgical Transaction, Niobium, Precipitation Kinetic, Recrystallization Kinetic
ISSN: 1543-1940
Cilt: 11
Sayı: 3
Sayfa: 387-402
Sınıflandırma:
18
Thermal processing of ferritic 5Mn steel for toughness at cryogenic temperatures
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
M. Niikura , J. W. Morris
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
It is shown that a thermal treatment which combines grain refinement with an intercritical temper (the 2BT treatment) may be used to achieve a promising combination of strength and toughness in a nickel-free ferritic steel of nominal composition Fe-5Mn-0.2Mo-0.04C at temperatures as low as -196 °C. The properties achieved are attributed to a symbiotic influence between the grain refinement treatment and the introduction of thermally stable retained austenite during intercritical tempering, a conclusion supported by a comparison of the results to those obtained with simpler heat treatments. The influence of carbon, manganese, and nickel additions to the base compositions are studied. An increase in carbon content above 0.04 wt pct causes a deterioration in toughness, as does an increase in manganese to 8 wt pct. An addition of 1 to 3 wt pct nickel is beneficial giving an increase in alloy strength at -196 °C without loss of toughness.
DOI: 10.1007/BF02654516
Anahtar Kelimeler: Austenite, Martensite, Metallurgical Transaction, Impact Toughness, Intercritical Tempering
ISSN: 1543-1940
Cilt: 11
Sayı: 9
Sayfa: 1531-1540
Sınıflandırma:
19
Electron microscopy study of the aging and first stage of tempering of high-carbon Fe-C martensite
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
O. N. C. Uwakweh , J. -M. R. Génin , J. -F. Silvain
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
Transmission electron microscopy (TEM) observations of 1.95 wt pct C martensite samples, aged at 330 and 352 K for 1 and 2 hours, respectively, confirm the fact that the two steps of aging, as evidenced by Mössbauer spectroscopy kinetics study, are due to clustering and subsequent long-range ordering. Streaks are observed along 〈203〉* directions during clustering, and in addition, two types of split superstructure spots appear during ordering at the advanced stage of aging. These are tentatively explained by a 1C-2Fe-1C-5Fe-1C-5Fe sequence of carbon and iron atoms arranged along [001]α′, which gives rise to antiphase domains with a 12a superperiod within the alternating carbon-rich and carbon-depleted regions, wherea is the lattice parameter of body-centered cubic (bcc) iron. The associated formula is Fe6C. In the first stage of tempering, the orthorhombic structure of the precipitated carbide is confirmed, while evidence of ordering as in Co2N is lacking. The Fe9C4 stoichiometry, which is close to the experimental Fe2.4C, is instead proposed forε- orη-carbide.
DOI: 10.1007/BF02658989
Anahtar Kelimeler: Carbide, Martensite, Metallurgical Transaction, Iron Atom, Habit Plane
ISSN: 1543-1940
Cilt: 22
Sayı: 4
Sayfa: 797-806
Sınıflandırma:
20
Effects of high temperature fatigue on microstructure and mechanical properties of a nickel-base precipitation hardened alloy
Dergi Makalesi

Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
S. K. HWang , C. S. Pande
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
Effects of high temperature strain controlled push-pull fatigue on the microstructure and mechanical properties of a nickel-base precipitation hardened alloy were studied. The fatigue deformation alone at 700 °C did not impair the mechanical properties of this alloy; however, a hold period ranging from one minute to one hour at tension-peak decreased the tensile ductility and the fracture toughness significantly. This was mainly attributed to grain boundary cavitation. Continuous fatigue resulted in dislocation bands, whereas hold-time fatigue caused a coherency loss iny’ precipitates. Implications of these microstructural changes for the residual mechanical properties are discussed.
DOI: 10.1007/BF02662369
Anahtar Kelimeler: Fatigue, Fracture Toughness, Metallurgical Transaction, Cavitation, Creep Deformation
ISSN: 1543-1940
Cilt: 14
Sayı: 10
Sayfa: 2021-2030
Sınıflandırma:
21
Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel
Dergi Makalesi

Dergi Makalesi Open Access
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
Kathrin Lefor , M. Walter , A. Weddeling , E. Hryha , S. Huth , S. Weber , L. Nyborg , W. Theisen
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Yıl:
2014
Higher contents can be alloyed by powder-metallurgical (PM) production via gas–solid interaction.
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Ni-free austenitic steels alloyed with Cr and Mn are an alternative to conventional Ni-containing steels. Nitrogen alloying of these steel grades is beneficial for several reasons such as increased strength and corrosion resistance. Low solubility in liquid and δ-ferrite restricts the maximal N-content that can be achieved via conventional metallurgy. Higher contents can be alloyed by powder-metallurgical (PM) production via gas–solid interaction. The performance of sintered parts is determined by appropriate sintering parameters. Three major PM-processing routes, hot isostatic pressing, supersolidus liquid phase sintering (SLPS), and solid-state sintering, were performed to study the influence of PM-processing route and N-content on densification, fracture, and mechanical properties. Sintering routes are designed with the assistance of thermodynamic calculations, differential thermal analysis, and residual gas analysis. Fracture surfaces were studied by X-ray photoelectron spectroscopy, secondary electron microscopy, and energy dispersive X-ray spectroscopy. Tensile tests and X-ray diffraction were performed to study mechanical properties and austenite stability. This study demonstrates that SLPS process reaches high densification of the high-Mn-containing powder material while the desired N-contents were successfully alloyed via gas–solid interaction. Produced specimens show tensile strengths >1000 MPa combined with strain to fracture of 60 pct and thus overcome the other tested production routes as well as conventional stainless austenitic or martensitic grades.
DOI: 10.1007/s11661-014-2701-7
Anahtar Kelimeler: Nitrogen Partial Pressure, Secondary Electron Microscopy, Iron Fraction, Sinter Route, Supersolidus Liquid Phase Sinter
ISSN: 1543-1940
Cilt: 46
Sayı: 3
Sayfa: 1154-1167
Sınıflandırma:
22
The effect of defects on the fatigue crack initiation process in two p/m superalloys: part ii. surface-subsurface transition
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
J. M. Hyzak , I. M. Bernstein
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
The change in fatigue failure initiation sites from a surface to subsurface location for two P/M nickel-based superalloys is analyzed. In particular the influences of defect size, shape, and population on the elevated temperature fatigue processes are assessed. The analysis shows that at high strain ranges, crack initiation occurs rapidly, and crack propagation rates determine the fatigue life and failure site. As a result, defect location (related to population) and size are the more important parameters. At lower strain ranges, however, crack initiation is critical in determining the failure origin, and this is primarily controlled by defect shape.
DOI: 10.1007/BF02642414
Anahtar Kelimeler: Fatigue, Metallurgical Transaction, Fatigue Life, Crack Initiation, Strain Range
ISSN: 1543-1940
Cilt: 13
Sayı: 1
Sayfa: 45-52
Sınıflandırma:
23
Density measurements as an assessment of creep damage and cavity growth
Dergi Makalesi

Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
David A. Miller , Terence G. Langdon
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
The change in density during creep of several polycrystalline metals may be correlated through the expression —Δρ/ρ =B(∈t/d)(σ/G)q exp (—Q gb /RT) where —Δρ is the density change, p is the original density, e is the strain,t is the time,d is the linear intercept grain size,σ is the applied stress,G is the shear modulus,Q gb is the activation energy for grain boundary diffusion,R is the gas constant,T is the absolute temperature, andB andq are constants withq ≃2 to 3. This expression is consistent with the theory of unconstrained grain boundary diffusion growth of cavities provided there is also concomitant strain-dependent nucleation. The expression does not support the power-law growth of cavities, growth by surface diffusion, or constrained grain boundary diffusion growth.
DOI: 10.1007/BF02654709
Anahtar Kelimeler: Metallurgical Transaction, Cavitation, Surface Diffusion, Boundary Diffusion, Stress Exponent
ISSN: 1543-1940
Cilt: 11
Sayı: 6
Sayfa: 955-962
Sınıflandırma:
24
Ordering transformations and mechanical properties of Ti 3 Ai and Ti 3 Al-Nb alloys
Dergi Makalesi

Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
S. M. L. Sastry , H. A. Lipsitt
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
Phase transformations and the kinetics of domain growth were studied in near stoichiometric Ti3Al and in a similar alloy containing about 5 at. pct Nb (Cb). The alloys were quenched from the β and from the α+ β fields and were subsequently annealed in the α2 field to study the ordering transformation. The critical temperature (T c) for ordering was found to be between 1125 and 1150° for both alloys. When quenched from aboveT c the microstructure of the stoichiometric compound contained massive martensite with small antiphase domains of average size 8 × 10— μm. On annealing the quenched structures in the range 700 to 1000°, domain coalescence occurred, the domains growing approximately as the square root of the annealing time. The activation energy for the domain growth process was found to be 64.6 ± 6 Kcal/mole (2.68 ± 0.25 × 105 J/mole). On quenching the alloy containing Nb the β transforms to a fine acicular martensite. On annealing, antiphase domain coalescence within the martensite plates and the simultaneous recrystallization of the martensite resulted in a fine subgrain structure even after annealing at 900° for up to 3 h. The mechanical properties and the fracture modes of the two alloys tested at 700° were correlated with the observed microstructural changes. The effects of Nb in this alloy are to slow the domain growth kinetics, to reduce the planarity of slip, and to increase nonbasal slip activity.
DOI: 10.1007/BF02644857
Anahtar Kelimeler: Martensite, Metallurgical Transaction, Martensite Plate, Domain Growth, Antiphase Domain
ISSN: 1543-1940
Cilt: 8
Sayı: 10
Sayfa: 1543-1552
Sınıflandırma:
25
Basal textures of the two grain size distributions in rolled ingot source beryllium with a duplex microstructure
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
Clinton R. Heiple
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical TRANSACTIONSA
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Kaydet
A selective recrystallization model is proposed to explain the origin of the stronger basal texture in rolled powder source beryllium compared to rolled ingot source beryllium. In addition, the model predicts that the large grains in the duplex microstructure of rolled ingot source beryllium will have a stronger basal texture than the small grains. The orientations of the large and small grains in rolled ingot beryllium have been measured with polarized light. The average concentration of basal poles lying within 20 deg of the sheet normal was 3.8 times random for the large grains and 2.1 times random for the small grains.
DOI: 10.1007/BF02659820
Anahtar Kelimeler: Beryllium, Basal Plane, Basal Texture, Duplex Microstructure, Metallurgical TRANSACTIONSA
ISSN: 1543-1940
Cilt: 7
Sayı: 12
Sayfa: 1887-1889
Sınıflandırma:
26
Gravitational influences on the liquid-state homogenization and solidification of aluminum antimonide
Dergi Makalesi

Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
Choh-Yi Ang , Lewis L. Lacy
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
Although the III-V compound aluminum antimonide (AlSb) shows promise as a highly efficient solar cell material, its semiconducting properties have not been exploited for device development due to difficulties in synthesizing a homogeneous stoichiometric compound and growing single crystals by conventional techniques. Liquid-state homogenization analysis, which examines the relative influence of gravitational flowvs interatomic diffusion, suggested that the microscopic inhomogeneities observed in commercial polycrystalline samples could be due to gravitational influences caused by large density differences between Al- and Sb-rich phases in earth based melts. Several liquid-state homogenization and solidification experiments performed on earth and a similar experiment performed during the Apollo-Soyuz Test Project mission in July 1975 verify this theoretical conclusion. Using comparative characterization techniques for identically processed low and one gravity samples of commercially available AlSb, this paper reports on gravitational influences, such as density driven convection or sedimentation, that cause microscopic phase separation and nonequilibrium conditions to exist in earth based melts of AlSb. The reported experiments have, likewise, shown that such phase separations can be greatly reduced in a low gravity environment and lead to major improvements in microscopic homogeneity of the re crystallized material.
DOI: 10.1007/BF02658314
Anahtar Kelimeler: Metallurgical Transaction, AlSb, Gravitational Influence, A1Sb Line, Aluminum Antimonide
ISSN: 1543-1940
Cilt: 10
Sayı: 5
Sayfa: 519-528
Sınıflandırma:
Fizik %80
27
Wrought aluminum-nickel alloys for high strength-high conductivity applications
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Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
P. K. Rohatgi , K. V. Prabhakar
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
Aluminum-Nickel alloys ranging from 0.06 pct to 6.1 pct (by wt) Ni have been developed for high strength-high conductivity applications. These alloys were produced by solidification in a permanent mold followed by homogenization, hot extrusion or hot rolling and cold drawing to wire form. This seguence of fabrication a) led to the production of fine fibrous dispersoids of NiAl3 as part of the Al-NiAl3 eutectic during the initial casting operation, b) permitted the retention of fine fibrous dispersiods of NiAl3 produced during casting without any significant coarsening during processing and c) led to uniform dispersion and general alignment of these fibrous dispersoids along a given direction in the product without any measurable fiber-matrix separation, extensive fiber-fragmentation or crack production in the matrix. These alloys can be processed to wire form as easily as aluminum and when processed by the above sequence, possess very attractive combination of high strength-high electrical conductivity. Tensile strengths range from 173 N/mm2 (at 0.6 pct Ni) to 241 N/mm2 (at 6.1 pct Ni) in combination with corresponding conductivity values between 62 pct IACS and 55.5 pct IACS. The wires also possess attractive yield strength; for instance, the 0.2 pct off-set strength of Al-6.1 pet Ni wire is 213 N/mm2. Using simple composite rules, the estimated strength and the conductivity of NiAl3 fibers were found to be 1380 N/mm2 and 18 pct IACS respectively, in these wires.
DOI: 10.1007/BF02661353
Anahtar Kelimeler: Metallurgical Transaction, NiAl, Control Impurity, Permanent Mold, Unidirectional Solidification
ISSN: 1543-1940
Cilt: 6
Sayı: 5
Sayfa: 1003-1008
Sınıflandırma:
28
Effect of long-term service exposure on microstructure and mechanical properties of a crmov steam turbine rotor steel
Dergi Makalesi

Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
A. Joarder , D. S. Sarma , N. S. Cheruvu
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
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Kaydet
The influence of prolonged service exposure on the microstructure and mechanical properties of a 1Cr-1Mo-0.25V steam turbine rotor steel has been studied. The samples for this study were taken from four locations of a rotor which had operated for 23 years. The operating temperatures at these locations were 288 °C, 425 °C, 510 °C, and 527 °C. The impact of retempering at 677 °C of steel exposed at 425 °C was also investigated. Service exposure at 288 °C brought no noticeable changes in either tensile properties or microstructure; the steel contained coarse bainitic cementite, extremely fine spheroidal MC, and thin platelets of M2C. Service exposure at 510 °C led to profuse precipitation of cementite along grain boundaries in addition to increasing M2C precipitation. These changes resulted in a slight decrease in the yield and tensile strengths and a marginal increase in ductility. Service exposure at 527 °C produced grain boundary precipitation of M23C6, coarsening of MC, and more profuse precipitation of M2C and caused a considerable decrease in strength and an increase in ductility. Retempering at 677 °C for 24 hours resulted in more precipitation of M23C6 and considerable coarsening of MC, without affecting further the size or shape of M2C. The strength of the steel decreased drastically and the reduction in area increased considerably due to retempering. These changes in microstructure and mechanical properties indicate that service exposure at 527 °C for 23 years did not produce a stable microstructure. The microstructure and mechanical properties of the rotor steel would continue to deteriorate in future operation.
DOI: 10.1007/BF02646505
Anahtar Kelimeler: Carbide, Metallurgical Transaction, Cementite, Select Area Diffraction, Rotor Steel
ISSN: 1543-1940
Cilt: 22
Sayı: 8
Sayfa: 1811-1820
Sınıflandırma:
29
Phosphorus induced 350°C embrittlement in an ultra high strength steel
Dergi Makalesi

Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
C. L. Briant , S. K. Banerji
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
Yayıncı Web Sitesi Tam Metin
Kaydet
DOI: 10.1007/BF02686416
Anahtar Kelimeler: Metallurgical Transaction, Cementite, Fracture Energy, Fracture Mode, Intergranular Fracture
ISSN: 1543-1940
Cilt: 10
Sayı: 1
Sayfa: 123-126
Sınıflandırma:
30
Mass transfer model of halogen doped incandescent lamps with application to the W-O-Br system
Dergi Makalesi

Dergi Makalesi
Kaynak:
Springer Link
Dergi:
Metallurgical and Materials Transactions A
Yazar(lar):
F. J. Harvey
Konu:
Metallic Materials, Characterization and Evaluation of Materials, Structural Materials, Surfaces and Interfaces, Nanotechnology
Metallurgical Transaction
Yayıncı Web Sitesi Tam Metin
Kaydet
A mass transfer model of halogen doped incandescent lamps is formulated. In this model, the transport processes occurring in these lamps are represented by diffusion and counter diffusion of gaseous species across the stagnant boundary layer surrounding the filament with simultaneous reactions at the bulb wall and the filament. The model is applied to the 500 watt-120 volt-T3 quartz halogen lamp geometry in which the initial gas phase is argon with small concentrations of oxygen and bromine. The tungsten flux from wall to filament andvice versa and, thus, the conditions of wall blackening are calculated as a function of the initial bromine and oxygen content, filament and wall temperature, total pressure and wall condensate,i.e., W(s), WO2(s), and WO3(s).
DOI: 10.1007/BF02656600
Anahtar Kelimeler: Metallurgical Transaction, Bromine, Wall Temperature, Incandescent Lamp, Initial Oxygen
ISSN: 1543-1940
Cilt: 7
Sayı: 8
Sayfa: 1167-1176
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