Pub Date : 1983-12-01DOI: 10.1179/030634583790420439
S. Chakravorty, D. West
AbstractAn investigation has been made of the constitution of the Ni–Mo–Ta system within the range 0–100 at.-%Mo and 0–40 at.-%Ta. The data are presented mainly as isothermal sections at 1523 and 1273 K, determined primarily by electron probe microanalysis and X-ray diffraction; some data for 1173 K are also included. The phases covered by the investigation are as follows: the Ni based solid solution γ, the Mo–Ta based solid solution, and intermetallic compounds based on Ni8Ta, Ni3Ta, Ni2Ta, Ni3Mo, and NiMo. A notable feature of the equilibria is the extensive solid solubility of Mo (up to ∼11 at.-%) in orthorhombic Ni3Ta in the range 1523–1173 K. In contrast to a previous report in the literature, it has also been shown that Ni3Ta and Ni3Mo do not form a continuous series of solid solutions at 1173 K. At 1523 and 1273 K, γ enters into equilibria with the following phases: Ni8(Ta, Mo), Ni3(Ta, Mo), and NiMo. The Ni3(Ta, Mo) phase enters into equilibria with γ, Ni8(Ta, Mo), Ni2Ta, NiMo, the Mo–Ta based sol...
{"title":"Constitution of Ni rich alloys in Ni–Mo–Ta system","authors":"S. Chakravorty, D. West","doi":"10.1179/030634583790420439","DOIUrl":"https://doi.org/10.1179/030634583790420439","url":null,"abstract":"AbstractAn investigation has been made of the constitution of the Ni–Mo–Ta system within the range 0–100 at.-%Mo and 0–40 at.-%Ta. The data are presented mainly as isothermal sections at 1523 and 1273 K, determined primarily by electron probe microanalysis and X-ray diffraction; some data for 1173 K are also included. The phases covered by the investigation are as follows: the Ni based solid solution γ, the Mo–Ta based solid solution, and intermetallic compounds based on Ni8Ta, Ni3Ta, Ni2Ta, Ni3Mo, and NiMo. A notable feature of the equilibria is the extensive solid solubility of Mo (up to ∼11 at.-%) in orthorhombic Ni3Ta in the range 1523–1173 K. In contrast to a previous report in the literature, it has also been shown that Ni3Ta and Ni3Mo do not form a continuous series of solid solutions at 1173 K. At 1523 and 1273 K, γ enters into equilibria with the following phases: Ni8(Ta, Mo), Ni3(Ta, Mo), and NiMo. The Ni3(Ta, Mo) phase enters into equilibria with γ, Ni8(Ta, Mo), Ni2Ta, NiMo, the Mo–Ta based sol...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"110 1","pages":"573-580"},"PeriodicalIF":0.0,"publicationDate":"1983-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90300911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-12-01DOI: 10.1179/030634583790420448
L. Błaż, T. Sakai, J. Jonas
AbstractOxygen free high conductivity (OFHC) and electrolytic tough pitch (ETP) copper specimens of different grain sizes (10–800 μm) were tested at various constant true strain rates in a modified Instron testing machine. The temperature range investigated was 725–1075 K. The effect of initial grain size on the transition from multiple to single peak flow was studied. The dependence of the stable dynamic grain size on the temperature corrected strain rate and the steady state stress was determined, as were the density of twins and of deformation bands. The density of twins decreased as the initial grain size was increased and when the recrystallization mechanism changed from static to dynamic. The density of deformation bands increased markedly with initial grain size. As the deformation bands are preferential nucleation sites for new dynamic grains, the results indicate that the initial effective grain size D o *
摘要:在改良的Instron试验机上，对不同晶粒尺寸(10 ~ 800 μm)的无氧高导电性(OFHC)和电韧性(ETP)铜试样进行了恒应变速率下的测试。实验温度范围为725 ~ 1075 K。研究了初始晶粒尺寸对多峰流向单峰流转变的影响。确定了稳定动态晶粒尺寸与温度修正应变速率和稳态应力的关系，以及孪晶和变形带的密度。孪晶密度随着初始晶粒尺寸的增大和再结晶机制由静态向动态转变而减小。变形带密度随初始晶粒尺寸的增大而显著增大。由于变形带是新动态晶粒的优先形核位置，结果表明，初始有效晶粒尺寸D o *
{"title":"Effect of initial grain size on dynamic recrystallization of copper","authors":"L. Błaż, T. Sakai, J. Jonas","doi":"10.1179/030634583790420448","DOIUrl":"https://doi.org/10.1179/030634583790420448","url":null,"abstract":"AbstractOxygen free high conductivity (OFHC) and electrolytic tough pitch (ETP) copper specimens of different grain sizes (10–800 μm) were tested at various constant true strain rates in a modified Instron testing machine. The temperature range investigated was 725–1075 K. The effect of initial grain size on the transition from multiple to single peak flow was studied. The dependence of the stable dynamic grain size on the temperature corrected strain rate and the steady state stress was determined, as were the density of twins and of deformation bands. The density of twins decreased as the initial grain size was increased and when the recrystallization mechanism changed from static to dynamic. The density of deformation bands increased markedly with initial grain size. As the deformation bands are preferential nucleation sites for new dynamic grains, the results indicate that the initial effective grain size D o *","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"59 1","pages":"609-616"},"PeriodicalIF":0.0,"publicationDate":"1983-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75050132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-12-01DOI: 10.1179/030634583790420411
T. Sheppard, M. Zaidi, G. H. Tan
AbstractThe microstructures of rapidly solidified Al–10Mg alloy powders have been observed by optical microscopy, scanning electron microscopy, and transmission electron microscopy. A technique is described which enabled individual powder particles to be made electron transparent. The alloy powders were then consolidated by cold compaction followed by hot extrusion using a wide range of temperature compensated strain rates. The microstructures evolved are reported and it is shown that there is a correlation between the microstructures and the process parameters. It is also shown that the initial powder structure is an important variable. Magnesium is retained in solid solution in the extrudate but is metastable at room temperature leading to decomposition over long periods of time. However, the very fine grain size observed (1–3 μm) is thermally stable up to 300°C and aging processes may be utilized to obtain acceptable structures.
{"title":"Microstructural aspects of extrusion of rapidly solidified Al–10Mg alloy powder","authors":"T. Sheppard, M. Zaidi, G. H. Tan","doi":"10.1179/030634583790420411","DOIUrl":"https://doi.org/10.1179/030634583790420411","url":null,"abstract":"AbstractThe microstructures of rapidly solidified Al–10Mg alloy powders have been observed by optical microscopy, scanning electron microscopy, and transmission electron microscopy. A technique is described which enabled individual powder particles to be made electron transparent. The alloy powders were then consolidated by cold compaction followed by hot extrusion using a wide range of temperature compensated strain rates. The microstructures evolved are reported and it is shown that there is a correlation between the microstructures and the process parameters. It is also shown that the initial powder structure is an important variable. Magnesium is retained in solid solution in the extrudate but is metastable at room temperature leading to decomposition over long periods of time. However, the very fine grain size observed (1–3 μm) is thermally stable up to 300°C and aging processes may be utilized to obtain acceptable structures.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"21 1","pages":"563-572"},"PeriodicalIF":0.0,"publicationDate":"1983-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82609573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-12-01DOI: 10.1179/030634583790420420
N. Okumura
AbstractMicromechanisms of transgranular cleavage fracture in ferritic steels have been investigated, particular attention being paid to the dependence of cleavage fracture stress σf on grain size over the range from 3·5 to 34·3 μm. It is found that σf increases less than linearly with d−1/2, where d is the grain diameter, whereas the Hall–Petch relation holds for the yield stress. Based on the experimental results, where σf was measured in the steels and their grain size and carbide size were changed independently, it is suggested that in the grain size range cited, the predominant mechanism was the propagation of a microcrack, which formed in the discrete carbide, into contiguous ferrite grains. The measured values of σf were discussed in a quantitative manner based on a model into which an equilibrium distribution of dislocations produced by the double pile-up mechanism was incorporated.
{"title":"Cleavage fracture of low carbon ferritic steels with fine grain size","authors":"N. Okumura","doi":"10.1179/030634583790420420","DOIUrl":"https://doi.org/10.1179/030634583790420420","url":null,"abstract":"AbstractMicromechanisms of transgranular cleavage fracture in ferritic steels have been investigated, particular attention being paid to the dependence of cleavage fracture stress σf on grain size over the range from 3·5 to 34·3 μm. It is found that σf increases less than linearly with d−1/2, where d is the grain diameter, whereas the Hall–Petch relation holds for the yield stress. Based on the experimental results, where σf was measured in the steels and their grain size and carbide size were changed independently, it is suggested that in the grain size range cited, the predominant mechanism was the propagation of a microcrack, which formed in the discrete carbide, into contiguous ferrite grains. The measured values of σf were discussed in a quantitative manner based on a model into which an equilibrium distribution of dislocations produced by the double pile-up mechanism was incorporated.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"13 1","pages":"581-589"},"PeriodicalIF":0.0,"publicationDate":"1983-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72911391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-12-01DOI: 10.1179/030634583790420394
P. Doig, P. Flewitt
Abstract The formation of α1 plates during isothermal aging of quenched, β′ phase, non-ferrous alloys has been taken to occur by a combined shear and diffusion regulated process. Cu–Zn alloy specimens (∼40 at.-%Zn) containing additions of Au up to ∼9 at.-% have been quenched to retain the β′ phase (B2) and isothermally aged in the temperature range 523–973 K to produce α1 plates and α rods. These precipitates have been examined using optical and transmission electron microscopy, and their compositions studied using high spatial resolution, STEM–EDS X-ray microanalysis on thin foil samples. The initially formed α1 plates have crystallographic characteristics similar to those of the martensitic product and are in agreement with the predictions of the phenomenological theory for martensite formation. The solute distributions between the parent β′ phase and the product α1 plates have been measured and these are discussed in relation to the mechanism for growth of the α1 plates.
{"title":"Solute redistributions associated with nucleation and growth of α1 plates in Cu–Zn and Au–Cu–Zn alloys","authors":"P. Doig, P. Flewitt","doi":"10.1179/030634583790420394","DOIUrl":"https://doi.org/10.1179/030634583790420394","url":null,"abstract":"Abstract The formation of α1 plates during isothermal aging of quenched, β′ phase, non-ferrous alloys has been taken to occur by a combined shear and diffusion regulated process. Cu–Zn alloy specimens (∼40 at.-%Zn) containing additions of Au up to ∼9 at.-% have been quenched to retain the β′ phase (B2) and isothermally aged in the temperature range 523–973 K to produce α1 plates and α rods. These precipitates have been examined using optical and transmission electron microscopy, and their compositions studied using high spatial resolution, STEM–EDS X-ray microanalysis on thin foil samples. The initially formed α1 plates have crystallographic characteristics similar to those of the martensitic product and are in agreement with the predictions of the phenomenological theory for martensite formation. The solute distributions between the parent β′ phase and the product α1 plates have been measured and these are discussed in relation to the mechanism for growth of the α1 plates.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"21 1","pages":"601-608"},"PeriodicalIF":0.0,"publicationDate":"1983-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75324469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-11-01DOI: 10.1179/030634583790420475
V. Guttmann, R. Bürgel
AbstractThe creep properties of the 32Ni–20Cr steel alloy 800 H have been investigated in the temperature range 900–1000°C. The results show that the creep behaviour is characterized by various irregularities. Structural analyses performed for selected creep conditions have revealed that significant structural instabilities become relevant during the creep process. As a result of the continuous ripening of the carbide precipitates the density of carbide pinned dislocations, which are assumed to provide an important contribution to strength, decreases as the creep process advances. In correlation with creep crack formation, a nitriding effect can occur during long term testing in air which is accompanied by an increase of the creep resistance.
{"title":"Creep–structural relationship in steel alloy 800 H at 900–1000°C","authors":"V. Guttmann, R. Bürgel","doi":"10.1179/030634583790420475","DOIUrl":"https://doi.org/10.1179/030634583790420475","url":null,"abstract":"AbstractThe creep properties of the 32Ni–20Cr steel alloy 800 H have been investigated in the temperature range 900–1000°C. The results show that the creep behaviour is characterized by various irregularities. Structural analyses performed for selected creep conditions have revealed that significant structural instabilities become relevant during the creep process. As a result of the continuous ripening of the carbide precipitates the density of carbide pinned dislocations, which are assumed to provide an important contribution to strength, decreases as the creep process advances. In correlation with creep crack formation, a nitriding effect can occur during long term testing in air which is accompanied by an increase of the creep resistance.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"121 1","pages":"549-555"},"PeriodicalIF":0.0,"publicationDate":"1983-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79441677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-11-01DOI: 10.1179/030634583790420457
Y. Maehara, Y. Ohmori, J. Murayama, N. Fujino, T. Kunitake
AbstractThe effects of alloying elements on σ phase precipitation in δ–γ duplex phase stainless steels have been studied with particular emphasis on the partitioning of alloying elements. Sigma phase precipitation occurred mainly through the eutectoid decomposition of δ into σ and γ phases. The concentrations of Cr, Mo, W, and Si in each phase decreased in the order σ, δ, then γ phase, while those of Ni and Mn decreased in the reverse order. The increase of Cr and Mo contents increased both the rate and the maximum amount of σ phase precipitation, while the increase of Ni content reduced the maximum amount of σ phase precipitation, though the rate of the precipitation was also accelerated. The effect of Ni can be explained in terms of the reduction in the δ phase fraction before aging, resulting in the enrichment of σ forming elements in the ferrite.
{"title":"Effects of alloying elements on σ phase precipitation in δ–γ duplex phase stainless steels","authors":"Y. Maehara, Y. Ohmori, J. Murayama, N. Fujino, T. Kunitake","doi":"10.1179/030634583790420457","DOIUrl":"https://doi.org/10.1179/030634583790420457","url":null,"abstract":"AbstractThe effects of alloying elements on σ phase precipitation in δ–γ duplex phase stainless steels have been studied with particular emphasis on the partitioning of alloying elements. Sigma phase precipitation occurred mainly through the eutectoid decomposition of δ into σ and γ phases. The concentrations of Cr, Mo, W, and Si in each phase decreased in the order σ, δ, then γ phase, while those of Ni and Mn decreased in the reverse order. The increase of Cr and Mo contents increased both the rate and the maximum amount of σ phase precipitation, while the increase of Ni content reduced the maximum amount of σ phase precipitation, though the rate of the precipitation was also accelerated. The effect of Ni can be explained in terms of the reduction in the δ phase fraction before aging, resulting in the enrichment of σ forming elements in the ferrite.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"112 1","pages":"541-548"},"PeriodicalIF":0.0,"publicationDate":"1983-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80722208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-11-01DOI: 10.1179/030634583790420493
K. Katagiri, R. Koterazawa, T. Yamada, T. Tsuboi
Abstract A study was made on the effects of intermittent overstressing on fatigue crack propagation using Fe specimens in as-normalized and as-stretched to 10% strain conditions. A few cycles of fully reversed overstress applied intermittently during very large numbers of cycles of understress below the threshold stress intensity caused significant acceleration of crack propagation. Ultrahigh voltage electron microscopic observation of the dislocation structures adjacent to fatigue crack tips revealed the occurrence of remarkable recovery during understressing and the formation of a radial band structure within the recovered region on overstressing. These structure changes induced by varying the stress are thought to be responsible for the acceleration of crack propagation in the material. The previously reported characteristics of acceleration of crack propagation under intermittent overstressing: (i) the increase of acceleration ratio R ac as the number of cycles of understress n 1 increases, and the sa...
{"title":"Changes in dislocation structures adjacent to fatigue crack tips induced by intermittent overstressing","authors":"K. Katagiri, R. Koterazawa, T. Yamada, T. Tsuboi","doi":"10.1179/030634583790420493","DOIUrl":"https://doi.org/10.1179/030634583790420493","url":null,"abstract":"Abstract A study was made on the effects of intermittent overstressing on fatigue crack propagation using Fe specimens in as-normalized and as-stretched to 10% strain conditions. A few cycles of fully reversed overstress applied intermittently during very large numbers of cycles of understress below the threshold stress intensity caused significant acceleration of crack propagation. Ultrahigh voltage electron microscopic observation of the dislocation structures adjacent to fatigue crack tips revealed the occurrence of remarkable recovery during understressing and the formation of a radial band structure within the recovered region on overstressing. These structure changes induced by varying the stress are thought to be responsible for the acceleration of crack propagation in the material. The previously reported characteristics of acceleration of crack propagation under intermittent overstressing: (i) the increase of acceleration ratio R ac as the number of cycles of understress n 1 increases, and the sa...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"7 1","pages":"556-562"},"PeriodicalIF":0.0,"publicationDate":"1983-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73719339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-11-01DOI: 10.1179/030634583790420466
P. W. Shelton, A. Wronski
AbstractCracked carbides (non-propagating microcracks) were observed in M2 type high speed steels deformed in four-point bending in the temperature range 17–600°C to ∼0·7% of the yield strain, i.e. to below the stress for macroscopic yielding and ductile or brittle fracture. Although the sintered M2 steel underwent a brittle–ductile transition at ∼300°C, no associated significant change in the fracture mechanism was detected. In all samples studied, cracking of individual carbides (nucleation of failure) was followed by the subcritical linking of these microcracks through the matrix, i.e. growth, and only then by catastrophic propagation, as a Griffith crack from an approximately semielliptical edge (or corner facet) fracture initiating region. Fracture mechanics analyses indicate the depth of this region to be in excess of the Griffith–Irwin flaw size, except for the brittle specimens. The region of subcritical crack growth is compared to the process zone reported for ceramics.
{"title":"Cracking in M2 high speed steel","authors":"P. W. Shelton, A. Wronski","doi":"10.1179/030634583790420466","DOIUrl":"https://doi.org/10.1179/030634583790420466","url":null,"abstract":"AbstractCracked carbides (non-propagating microcracks) were observed in M2 type high speed steels deformed in four-point bending in the temperature range 17–600°C to ∼0·7% of the yield strain, i.e. to below the stress for macroscopic yielding and ductile or brittle fracture. Although the sintered M2 steel underwent a brittle–ductile transition at ∼300°C, no associated significant change in the fracture mechanism was detected. In all samples studied, cracking of individual carbides (nucleation of failure) was followed by the subcritical linking of these microcracks through the matrix, i.e. growth, and only then by catastrophic propagation, as a Griffith crack from an approximately semielliptical edge (or corner facet) fracture initiating region. Fracture mechanics analyses indicate the depth of this region to be in excess of the Griffith–Irwin flaw size, except for the brittle specimens. The region of subcritical crack growth is compared to the process zone reported for ceramics.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"13 1","pages":"533-540"},"PeriodicalIF":0.0,"publicationDate":"1983-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82840780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1983-11-01DOI: 10.1179/030634583790420501
L. Edwards, J. Martin
Abstract The fatigue crack propagation characteristics of three peak aged Al–Mg–Si alloys have been determined. One was of essentially ternary composition, the others contained increasing volume fractions of 0·1 μm dia. dispersoid particles. The stress intensity thresholds for fatigue crack propagation ∆K TH increased with increasing volume fraction of dispersoid. At low and intermediate values of stress intensity ∆K, the crack growth rate decreased as the volume fraction of dispersoid increased. However, at high values of ∆K, void coalescence around coarse particles could outweigh the beneficial effect of the dispersoids. The degree of intergranular fracture occurring in the alloys was shown to be dependent on the maximum stress intensity in the fatigue cycle K max. The micromechanism of intergranular fracture was identified as microvoid coalescence along the grain boundary precipitate free zone. The concept of a semicohesive zone ahead of the fatigue crack tip is shown to be useful in modelling the micr...
{"title":"Effect of dispersoids on fatigue crack propagation in aluminium alloys","authors":"L. Edwards, J. Martin","doi":"10.1179/030634583790420501","DOIUrl":"https://doi.org/10.1179/030634583790420501","url":null,"abstract":"Abstract The fatigue crack propagation characteristics of three peak aged Al–Mg–Si alloys have been determined. One was of essentially ternary composition, the others contained increasing volume fractions of 0·1 μm dia. dispersoid particles. The stress intensity thresholds for fatigue crack propagation ∆K TH increased with increasing volume fraction of dispersoid. At low and intermediate values of stress intensity ∆K, the crack growth rate decreased as the volume fraction of dispersoid increased. However, at high values of ∆K, void coalescence around coarse particles could outweigh the beneficial effect of the dispersoids. The degree of intergranular fracture occurring in the alloys was shown to be dependent on the maximum stress intensity in the fatigue cycle K max. The micromechanism of intergranular fracture was identified as microvoid coalescence along the grain boundary precipitate free zone. The concept of a semicohesive zone ahead of the fatigue crack tip is shown to be useful in modelling the micr...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"19 1","pages":"511-518"},"PeriodicalIF":0.0,"publicationDate":"1983-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76661529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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