Pub Date : 1900-01-01DOI: 10.1179/MSC.1967.1.1.127
P. Barrand
AbstractGrain-boundary relaxations have been studied, using a free-decay, internal-friction technique, in chromium-iron alloys containing 16 and 22.5% chromium. Values of δE, the relaxation strength, Q, the activation energy, and τ0, a pre-exponential factor, were calculated. The data are compared with previous results obtained by the author on other iron-chromium alloys, and the influence of σ phase formation on the relaxations is briefly assessed.
{"title":"Grain-Boundary Damping in 16 and 22.5% Chromium-Iron Alloys","authors":"P. Barrand","doi":"10.1179/MSC.1967.1.1.127","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.127","url":null,"abstract":"AbstractGrain-boundary relaxations have been studied, using a free-decay, internal-friction technique, in chromium-iron alloys containing 16 and 22.5% chromium. Values of δE, the relaxation strength, Q, the activation energy, and τ0, a pre-exponential factor, were calculated. The data are compared with previous results obtained by the author on other iron-chromium alloys, and the influence of σ phase formation on the relaxations is briefly assessed.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116041755","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 : 1900-01-01DOI: 10.1179/030634573790445541
D. W. Clegg, R. Buckley
AbstractThe rates of ordering and antiphase domain coalescence during isothermal annealing of quenched equiatomic iron–cobalt and iron–cobalt–vanadium alloys have been studied in the range 400–600° C. Experimental techniques included X-ray diffraction (superlattice line intensity and breadth, and lattice parameter) and measurement of magnetic saturation moment. Amounts of vanadium up to 2.5% do not significantly affect the ordering kinetics in these alloys. It is suggested that the transformation bcc → L20 in this system occurs by a homogeneous process rather than by nucleation and growth of ordered domains. Rates of antiphase domain coalescence are affected by vanadium. Coalescence is very rapid in FeCo below 550°C but is relatively slow in FeCo and FeCo-V above 550°C, when a linear (domain size) vs. time relationship is obeyed. The effect of vanadium on the equilibrium degree of order in the range 300–900°C has been assessed on the basis of specific-heat, lattice-parameter, and magnetic-saturation measu...
{"title":"The Disorder → Order Transformation in Iron–Cobalt-Based Alloys","authors":"D. W. Clegg, R. Buckley","doi":"10.1179/030634573790445541","DOIUrl":"https://doi.org/10.1179/030634573790445541","url":null,"abstract":"AbstractThe rates of ordering and antiphase domain coalescence during isothermal annealing of quenched equiatomic iron–cobalt and iron–cobalt–vanadium alloys have been studied in the range 400–600° C. Experimental techniques included X-ray diffraction (superlattice line intensity and breadth, and lattice parameter) and measurement of magnetic saturation moment. Amounts of vanadium up to 2.5% do not significantly affect the ordering kinetics in these alloys. It is suggested that the transformation bcc → L20 in this system occurs by a homogeneous process rather than by nucleation and growth of ordered domains. Rates of antiphase domain coalescence are affected by vanadium. Coalescence is very rapid in FeCo below 550°C but is relatively slow in FeCo and FeCo-V above 550°C, when a linear (domain size) vs. time relationship is obeyed. The effect of vanadium on the equilibrium degree of order in the range 300–900°C has been assessed on the basis of specific-heat, lattice-parameter, and magnetic-saturation measu...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116054786","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 : 1900-01-01DOI: 10.1179/030634571790439405
B. Burton
AbstractThe creep behaviour of powder-compacted copper and copper containing 0.5, 1.0 and 1.5 vol.-%alumina has been investigated in the range where the stress-directed lattice diffusion of vacancies is expected to control. Addition of alumina particles is shown to change the initial flow characteristics from Newtonian, where the creep rate έ is proportional to the applied stress σ, to Bingham type, where έ is proportional to an effective stress σέ. This effective stress is defined by σέ = σ − σ0, where σ0 is a threshold value that increases linearly with volume fraction of alumina and below which no deformation occurs. The proportionality constant between έ and σE is shown to be identical to that between έ and σ and is given by the Nabarro-Herring equation as BΩD/d2 kT, where B is a numerical constant, Ω the atomic volume, D the lattice self-diffusion coefficient, D the grain size, and kT has its usual meaning. Above the threshold stress, creep rate decreases with strain and this curvature is more pronou...
{"title":"The Influence of Alumina Dispersions on the Diffusion-Creep Behaviour of Polycrystalline Copper","authors":"B. Burton","doi":"10.1179/030634571790439405","DOIUrl":"https://doi.org/10.1179/030634571790439405","url":null,"abstract":"AbstractThe creep behaviour of powder-compacted copper and copper containing 0.5, 1.0 and 1.5 vol.-%alumina has been investigated in the range where the stress-directed lattice diffusion of vacancies is expected to control. Addition of alumina particles is shown to change the initial flow characteristics from Newtonian, where the creep rate έ is proportional to the applied stress σ, to Bingham type, where έ is proportional to an effective stress σέ. This effective stress is defined by σέ = σ − σ0, where σ0 is a threshold value that increases linearly with volume fraction of alumina and below which no deformation occurs. The proportionality constant between έ and σE is shown to be identical to that between έ and σ and is given by the Nabarro-Herring equation as BΩD/d2 kT, where B is a numerical constant, Ω the atomic volume, D the lattice self-diffusion coefficient, D the grain size, and kT has its usual meaning. Above the threshold stress, creep rate decreases with strain and this curvature is more pronou...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116143154","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}
Abstract The recovery of quenched-in vacancies in a number of aluminium–indium alloys based upon zone-refined aluminium has been studied by means of resistivity measurements and transmission electron microscopy. Recovery is shown to occur in three stages: (a) solute–vacancy association, (b) the formation of prismatic dislocation loops, and (c) the annealing out of the loops. The kinetics of the first stage are analysed and for low quench temperatures found to be consistent with a modified Damask and Dienes theory. Consideration is given to the possibility of solute–vacancy association occurring during quenching. From loop-density measurements the indium–vacancy binding energy is roughly estimated to be 0·27 eV.
{"title":"Vacancy Recovery in Quenched Aluminium–Indium Alloys","authors":"F. C. Duckworth, T. Ramachandran, J. Burke","doi":"10.1179/MSC.1969.3.1.61","DOIUrl":"https://doi.org/10.1179/MSC.1969.3.1.61","url":null,"abstract":"Abstract The recovery of quenched-in vacancies in a number of aluminium–indium alloys based upon zone-refined aluminium has been studied by means of resistivity measurements and transmission electron microscopy. Recovery is shown to occur in three stages: (a) solute–vacancy association, (b) the formation of prismatic dislocation loops, and (c) the annealing out of the loops. The kinetics of the first stage are analysed and for low quench temperatures found to be consistent with a modified Damask and Dienes theory. Consideration is given to the possibility of solute–vacancy association occurring during quenching. From loop-density measurements the indium–vacancy binding energy is roughly estimated to be 0·27 eV.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116455022","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 : 1900-01-01DOI: 10.1179/030634572790445902
D. Chung, M. Chaturvedi
AbstractThe quench-ageing behaviour of a new Co–Ni–Cr-base high-temperature alloy containing Ti has been studied. The as-quenched structure of the alloy was fcc, and on ageing between 700 and 900° C (973 and 1173 K) the main strengthening phase was observed to be an ordered fcc γ′ phase. On overageing, this phase transforms to a stable hexagonal Ni3Ti η phase. The grain boundaries provide nucleation sites for the cellular precipitation of η phase. TiC and M23C6 carbides were also observed. However, during overageing TiC transforms to M23C6 carbides.
{"title":"Quench-Ageing Behaviour of 40Co–38Ni–17Cr–5Ti Alloy","authors":"D. Chung, M. Chaturvedi","doi":"10.1179/030634572790445902","DOIUrl":"https://doi.org/10.1179/030634572790445902","url":null,"abstract":"AbstractThe quench-ageing behaviour of a new Co–Ni–Cr-base high-temperature alloy containing Ti has been studied. The as-quenched structure of the alloy was fcc, and on ageing between 700 and 900° C (973 and 1173 K) the main strengthening phase was observed to be an ordered fcc γ′ phase. On overageing, this phase transforms to a stable hexagonal Ni3Ti η phase. The grain boundaries provide nucleation sites for the cellular precipitation of η phase. TiC and M23C6 carbides were also observed. However, during overageing TiC transforms to M23C6 carbides.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122315701","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 : 1900-01-01DOI: 10.1179/MSC.1967.1.1.182
M. D. Morton, G. Leak
AbstractZener relaxation peaks have been observed by low-frequency internal-friction measurements in seven polycrystalline copper-gold alloys. Measurements of associated activation energies and relaxation strengths show maxima at the equiatomic composition of 50.5 kcal/mole and 0.4 (at 400° C), respectively. The activation energies for the relatively dilute alloys were slightly less than or equal to those reported for tracer-diffusion studies. A large variation in τ0 with composition correlates roughly with entropy changes estimated from the temperature-dependence of the shear modulus. The maximum relaxation strength at equiatomic composition is in qualitative agreement with the predictions of Zener (“Elasticity and Anelasticity of Metals”, p. 106. 1948: Chicago (University Press)) and Shmatov (Physics Metals Metallography, 1960, 9, 98). Estimation of the ordering temperatures for Cu3Au and two off-stoichiometric alloys from the temperature-dependence of the relaxation strength has yielded results that co...
{"title":"Zener Relaxations in the Copper-Gold System","authors":"M. D. Morton, G. Leak","doi":"10.1179/MSC.1967.1.1.182","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.182","url":null,"abstract":"AbstractZener relaxation peaks have been observed by low-frequency internal-friction measurements in seven polycrystalline copper-gold alloys. Measurements of associated activation energies and relaxation strengths show maxima at the equiatomic composition of 50.5 kcal/mole and 0.4 (at 400° C), respectively. The activation energies for the relatively dilute alloys were slightly less than or equal to those reported for tracer-diffusion studies. A large variation in τ0 with composition correlates roughly with entropy changes estimated from the temperature-dependence of the shear modulus. The maximum relaxation strength at equiatomic composition is in qualitative agreement with the predictions of Zener (“Elasticity and Anelasticity of Metals”, p. 106. 1948: Chicago (University Press)) and Shmatov (Physics Metals Metallography, 1960, 9, 98). Estimation of the ordering temperatures for Cu3Au and two off-stoichiometric alloys from the temperature-dependence of the relaxation strength has yielded results that co...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122356358","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 : 1900-01-01DOI: 10.1179/MSC.1970.4.1.147
R. H. Cook, A. Entwisle
AbstractDeformation characteristics of Cu–1 at.-% In single crystals are presented for a range of orientations at temperatures from 77 to 473 K. Macroscopic slip commences with a yield point followed by a Luders strain. The shear during the Luders strain is markedly orientation-dependent and increases with decreasing temperature. Subsequent to the Luders strain, work-hardening Stages I and II are seen in nearly all cases. Stage II is followed by a stage of conjugate slip which often begins with an inhomogeneous propagation. Subsequent to this propagation, or in its absence, hardening on the conjugate system proceeds in a linear fashion at a rate of between 3 and 7 kgf/mm2 (29 and 69 MN/m2), dependent on orientation. The inter-relationship of Luders strain and hardening rate during Stage I is discussed in detail. Models of the yield point, based on dislocation multiplication effects, account fairly well for the observed orientation-dependence of Luders strain at 293 K, but modifications are necessary to ex...
{"title":"Yield-Point Behaviour in Cu–1 at.-% In Single Crystals","authors":"R. H. Cook, A. Entwisle","doi":"10.1179/MSC.1970.4.1.147","DOIUrl":"https://doi.org/10.1179/MSC.1970.4.1.147","url":null,"abstract":"AbstractDeformation characteristics of Cu–1 at.-% In single crystals are presented for a range of orientations at temperatures from 77 to 473 K. Macroscopic slip commences with a yield point followed by a Luders strain. The shear during the Luders strain is markedly orientation-dependent and increases with decreasing temperature. Subsequent to the Luders strain, work-hardening Stages I and II are seen in nearly all cases. Stage II is followed by a stage of conjugate slip which often begins with an inhomogeneous propagation. Subsequent to this propagation, or in its absence, hardening on the conjugate system proceeds in a linear fashion at a rate of between 3 and 7 kgf/mm2 (29 and 69 MN/m2), dependent on orientation. The inter-relationship of Luders strain and hardening rate during Stage I is discussed in detail. Models of the yield point, based on dislocation multiplication effects, account fairly well for the observed orientation-dependence of Luders strain at 293 K, but modifications are necessary to ex...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122506771","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 : 1900-01-01DOI: 10.1179/030634572790445731
P. Wilkes, C. M. Sargent
AbstractThe calculation of pair potentials for aluminium by a Fourier transform of various energy-wave-number characteristics is described. The potentials here tabulated have been tested by calculation of stacking-fault and twin energies. The results are in close agreement with experiment, giving γintrinsic 14.0 μJ/cm2, γextrinsic 13.0 μJ/cm2,and γtwin 6.5 μJ/cm2.
{"title":"A Calculation of the Stacking-Fault and Twin Energies for Aluminium","authors":"P. Wilkes, C. M. Sargent","doi":"10.1179/030634572790445731","DOIUrl":"https://doi.org/10.1179/030634572790445731","url":null,"abstract":"AbstractThe calculation of pair potentials for aluminium by a Fourier transform of various energy-wave-number characteristics is described. The potentials here tabulated have been tested by calculation of stacking-fault and twin energies. The results are in close agreement with experiment, giving γintrinsic 14.0 μJ/cm2, γextrinsic 13.0 μJ/cm2,and γtwin 6.5 μJ/cm2.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122176326","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 : 1900-01-01DOI: 10.1179/030634573790445514
J. E. Harris
AbstractIt has been demonstrated repeatedly that diffusion creep is inhibited when a second phase is present in a polycrystalline sample. It is proposed that this inhibition is due to the precipitates affecting adversely the ability of the high-angle grain boundaries to absorb or emit vacancies. During strain, precipitates are collected at those boundaries which are parallel to the tensilestress axis and this results in the diffusion-creep rate falling continuously. A simple model is presented which assumes that deformation can proceed only by the generation of dislocations in the matrix adjacent to the intergranular precipitates. The derived relationship between strain (e) and time (t) is e = (α/β) (1 – exp – J3t), where α and β are constants for a given specimen and test condition. The diffusional strain predicted from this equation was found to be in reasonable agreement with that observed in a creep specimen of a magnesium – 0.55 wt.-% zirconium alloy. The theoretical model can also be applied to the ...
{"title":"The Inhibition of Diffusion Creep by Precipitates","authors":"J. E. Harris","doi":"10.1179/030634573790445514","DOIUrl":"https://doi.org/10.1179/030634573790445514","url":null,"abstract":"AbstractIt has been demonstrated repeatedly that diffusion creep is inhibited when a second phase is present in a polycrystalline sample. It is proposed that this inhibition is due to the precipitates affecting adversely the ability of the high-angle grain boundaries to absorb or emit vacancies. During strain, precipitates are collected at those boundaries which are parallel to the tensilestress axis and this results in the diffusion-creep rate falling continuously. A simple model is presented which assumes that deformation can proceed only by the generation of dislocations in the matrix adjacent to the intergranular precipitates. The derived relationship between strain (e) and time (t) is e = (α/β) (1 – exp – J3t), where α and β are constants for a given specimen and test condition. The diffusional strain predicted from this equation was found to be in reasonable agreement with that observed in a creep specimen of a magnesium – 0.55 wt.-% zirconium alloy. The theoretical model can also be applied to the ...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117321697","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 : 1900-01-01DOI: 10.1179/MSC.1967.1.1.140
R. Skelton
AbstractHigh-frequency (10–1700 c/s) push/pull fatigue tests on a magnesium alloy at 0.75 of the melting point show that the rate of fatigue-hardening generally increases with increasing frequency and stress level. The time to onset of major crack propagation is virtually independent of frequency, though decreasing slightly at the higher frequencies. Beyond this point, the rate of crack propagation may be either time- or cycle-dependent, according to stress level. Fatigue specimens show marked grain growth at a rate that increases with increasing stress level. High-frequency tests are associated with less growth and enhanced boundary cavitation. Smaller grains give rise to less overall plastic strain than large grains and evidence is presented of grain-boundary sliding during fatigue.
{"title":"The Fatigue of Magnesium at High Temperature","authors":"R. Skelton","doi":"10.1179/MSC.1967.1.1.140","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.140","url":null,"abstract":"AbstractHigh-frequency (10–1700 c/s) push/pull fatigue tests on a magnesium alloy at 0.75 of the melting point show that the rate of fatigue-hardening generally increases with increasing frequency and stress level. The time to onset of major crack propagation is virtually independent of frequency, though decreasing slightly at the higher frequencies. Beyond this point, the rate of crack propagation may be either time- or cycle-dependent, according to stress level. Fatigue specimens show marked grain growth at a rate that increases with increasing stress level. High-frequency tests are associated with less growth and enhanced boundary cavitation. Smaller grains give rise to less overall plastic strain than large grains and evidence is presented of grain-boundary sliding during fatigue.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129600417","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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