Pub Date : 1900-01-01DOI: 10.1179/030634571790439487
C. V. D. Wekken, R. Taggart, D. H. Polonis
AbstractThe changes in the electrical resistivity of nickel-rich Ni-Nb alloys due to the formation of short-range order exhibit an anomalous dependence on the solute concentration. This anomaly can be explained by the formation of embryos of long-range order of the type Ni8Nb in alloys approaching the NisNb composition and near the critical temperature for long-range order. In the absence of a critical concentration of quenched-in vacancies, short-range-order formation only has been detected during ageing below the critical temperature.
{"title":"Short-Range Order and the Nucleation of Long-Range Order in Ni-Rich Nickel-Niobium Alloys","authors":"C. V. D. Wekken, R. Taggart, D. H. Polonis","doi":"10.1179/030634571790439487","DOIUrl":"https://doi.org/10.1179/030634571790439487","url":null,"abstract":"AbstractThe changes in the electrical resistivity of nickel-rich Ni-Nb alloys due to the formation of short-range order exhibit an anomalous dependence on the solute concentration. This anomaly can be explained by the formation of embryos of long-range order of the type Ni8Nb in alloys approaching the NisNb composition and near the critical temperature for long-range order. In the absence of a critical concentration of quenched-in vacancies, short-range-order formation only has been detected during ageing below the critical temperature.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"15 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120989645","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: 10.1179/030634571790439685
G. Purdy
AbstractThe diffusional growth of Widmanstatten α rods from ordered β-brass has been studied by means of deep-etching techniques and scanning electron microscopy. Slow-growing rods have large tip radii. The lengthening rates and tip radii of fast-growing rods are in good accord with a local-equilibrium model in which account is taken of non-ideal thermodynamic behaviour.
{"title":"Widmanstätten Precipitation from Non-Ideal Solid Solution: αinβ-CuZn","authors":"G. Purdy","doi":"10.1179/030634571790439685","DOIUrl":"https://doi.org/10.1179/030634571790439685","url":null,"abstract":"AbstractThe diffusional growth of Widmanstatten α rods from ordered β-brass has been studied by means of deep-etching techniques and scanning electron microscopy. Slow-growing rods have large tip radii. The lengthening rates and tip radii of fast-growing rods are in good accord with a local-equilibrium model in which account is taken of non-ideal thermodynamic behaviour.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"41 2 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":"124153017","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}
AbstractCoarse-grained (∼0·3 mm) α-titanium has been fatigued in tension/compression about a zero mean load at a frequency of ∼ 100 Hz at room temperature. A combined metallographic and microbeam X-ray analysis revealed the presence of { 10 1 ¯ 2 } -, { 11 2 ¯ 1 } -, and { 11 2 ¯ 2 } - type twins. In internal grains, i.e. grains completely constrained by surrounding material, fatigue _damage was observed to be associated with the { 11 2 ¯
{"title":"On the Formation of Internal Fatigue Damage in Association with Twins in α-Titanium","authors":"C. Beevers, M. Halliday","doi":"10.1179/MSC.1969.3.1.74","DOIUrl":"https://doi.org/10.1179/MSC.1969.3.1.74","url":null,"abstract":"AbstractCoarse-grained (∼0·3 mm) α-titanium has been fatigued in tension/compression about a zero mean load at a frequency of ∼ 100 Hz at room temperature. A combined metallographic and microbeam X-ray analysis revealed the presence of { 10 1 ¯ 2 } -, { 11 2 ¯ 1 } -, and { 11 2 ¯ 2 } - type twins. In internal grains, i.e. grains completely constrained by surrounding material, fatigue _damage was observed to be associated with the { 11 2 ¯","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"49 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":"127512388","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}
AbstractThe surface energy of iron-3% silicon alloy has been determined as 1940 ± 600 erg. cm−2 for the range 1075–1325° C by measuring the decay kinetics of multiple scratches on single crystals near (110) orientation during vacuum annealing. Mass transport occurred mainly by volume diffusion in the alloy. Surface-energy values from single scratches were higher by ∼ 20% than those from multiple scratches, probably because of inadequacies in the single-scratch analysis. Facets formed where the smoothed scratch profile contained the (110) plane at the highest temperature (1300° C) only and for the crystal nearest to (110) orientation. It was noted that extended striations formed on a single crystal near (100) orientation on annealing at 1200° C, in the direction for which a small surface tilt would expose the (100) plane. These observations suggest that the γ-plot has a deeper cusp at (100) than at (110) under the annealing conditions prevailing.
{"title":"The Surface Energy of Iron-3% Silicon by Surface-Relaxation Measurements","authors":"B. Mills, H. Jones, G. Leak","doi":"10.1179/MSC.1967.1.1.9","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.9","url":null,"abstract":"AbstractThe surface energy of iron-3% silicon alloy has been determined as 1940 ± 600 erg. cm−2 for the range 1075–1325° C by measuring the decay kinetics of multiple scratches on single crystals near (110) orientation during vacuum annealing. Mass transport occurred mainly by volume diffusion in the alloy. Surface-energy values from single scratches were higher by ∼ 20% than those from multiple scratches, probably because of inadequacies in the single-scratch analysis. Facets formed where the smoothed scratch profile contained the (110) plane at the highest temperature (1300° C) only and for the crystal nearest to (110) orientation. It was noted that extended striations formed on a single crystal near (100) orientation on annealing at 1200° C, in the direction for which a small surface tilt would expose the (100) plane. These observations suggest that the γ-plot has a deeper cusp at (100) than at (110) under the annealing conditions prevailing.","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":"127466613","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: 10.1179/030634568790443189
P. Feltham, C. J. Spears
AbstractStress relaxation at constant strains has been studied in crystals of copper and α-brasses containing 10, 20, or 30 at.-% zinc at 77,200, and 291° K after consecutive small plastic deformations. Close to the yield point the relaxation was generally within 1% of the applied stress, but at large deformations, notably within the third stage of work-hardening, it attained ∼ 10%. Any given relaxation was observed for ∼ 1000 sec, over most of which period the decay of the stress was logarithmic in time. Energy barriers of the activated process were from ∼ 0.08 eV for copper and 0.2–0.3 eV for brasses. Their significance is discussed in terms of a model in which unpinning of dislocations from rows of solute atoms is the principal process determining the relaxation rate.
{"title":"Stress Relaxation in Single Crystals of Copper and α-Brasses","authors":"P. Feltham, C. J. Spears","doi":"10.1179/030634568790443189","DOIUrl":"https://doi.org/10.1179/030634568790443189","url":null,"abstract":"AbstractStress relaxation at constant strains has been studied in crystals of copper and α-brasses containing 10, 20, or 30 at.-% zinc at 77,200, and 291° K after consecutive small plastic deformations. Close to the yield point the relaxation was generally within 1% of the applied stress, but at large deformations, notably within the third stage of work-hardening, it attained ∼ 10%. Any given relaxation was observed for ∼ 1000 sec, over most of which period the decay of the stress was logarithmic in time. Energy barriers of the activated process were from ∼ 0.08 eV for copper and 0.2–0.3 eV for brasses. Their significance is discussed in terms of a model in which unpinning of dislocations from rows of solute atoms is the principal process determining the relaxation rate.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"2010 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":"127350420","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.1967.1.1.172
R. Lagneborg
AbstractBreaks in the stress/rupture time and stress/creep rate relation are known to occur during high-temperature creep. In the present work these deflections are explained in terms of different stress-dependences of the intracrystalline deformation rate and the rate of grain-boundary sliding. The transition from trans- to intercrystalline fracture, which coincides, at least approximately, with these breaks, is suggested to be due to the increased grain-boundary sliding at stresses below the break.
{"title":"Deviations from Linearity in Creep-Rupture Curves","authors":"R. Lagneborg","doi":"10.1179/MSC.1967.1.1.172","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.172","url":null,"abstract":"AbstractBreaks in the stress/rupture time and stress/creep rate relation are known to occur during high-temperature creep. In the present work these deflections are explained in terms of different stress-dependences of the intracrystalline deformation rate and the rate of grain-boundary sliding. The transition from trans- to intercrystalline fracture, which coincides, at least approximately, with these breaks, is suggested to be due to the increased grain-boundary sliding at stresses below the break.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"37 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":"117035374","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: 10.1179/030634573790445550
J. Robinson, C. Beevers
AbstractLow-stress fatigue-crack-propagation tests have been carried out on three commercially pure α-titaniumalloys. It was found that decreasing load ratio (R), increasing grain size, and increasing interstitial alloying content could all produce significant reductions in growth rate over the ∆K range studied (4–20 MN/m2). The conclusion was reached that the fatigue-fracture process comprised two stages: (1) the formation of relatively planar facets (primarily ∆K-controlled) and (2) their interconnection by a mechanism involving plastic tearing (primarily K max-controlled). Scanning electron microscope examination of the fatigue-fracture surfaces revealed that the orientations of individual grains exerted a considerable influence on fracture-surface morphology. This effect occurred when the scale of reversed plasticity at the crack tip was of the order of, or less than, the grain size. A transition in fracturesurface appearance occurred in all specimens at an approximately constant value of growth rate ...
{"title":"The Effects of Load Ratio, Interstitial Content, and Grain Size on Low-Stress Fatigue-Crack Propagation in α-Titanium","authors":"J. Robinson, C. Beevers","doi":"10.1179/030634573790445550","DOIUrl":"https://doi.org/10.1179/030634573790445550","url":null,"abstract":"AbstractLow-stress fatigue-crack-propagation tests have been carried out on three commercially pure α-titaniumalloys. It was found that decreasing load ratio (R), increasing grain size, and increasing interstitial alloying content could all produce significant reductions in growth rate over the ∆K range studied (4–20 MN/m2). The conclusion was reached that the fatigue-fracture process comprised two stages: (1) the formation of relatively planar facets (primarily ∆K-controlled) and (2) their interconnection by a mechanism involving plastic tearing (primarily K max-controlled). Scanning electron microscope examination of the fatigue-fracture surfaces revealed that the orientations of individual grains exerted a considerable influence on fracture-surface morphology. This effect occurred when the scale of reversed plasticity at the crack tip was of the order of, or less than, the grain size. A transition in fracturesurface appearance occurred in all specimens at an approximately constant value of growth rate ...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"109 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":"131555224","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.1967.1.1.198
P. Goodhew, P. Dobson, R. Smallman
AbstractThe extrinsic stacking-fault energy of aluminium has been determined from the isothermal annealing of double-faulted dislocation loops in the electron microscope and found to be 30% greater than the intrinsic energy. The observed rarity of extrinsic faulting in thin foils is accounted for in terms of a nucleation barrier to the formation of an extrinsic fault. Several previous observations of extrinsic faults, some of which have been taken to imply a higher extrinsic stacking-fault energy, are re-examined in the light of this barrier.
{"title":"Extrinsic Stacking-Fault Energies in F.C.C. Materials","authors":"P. Goodhew, P. Dobson, R. Smallman","doi":"10.1179/MSC.1967.1.1.198","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.198","url":null,"abstract":"AbstractThe extrinsic stacking-fault energy of aluminium has been determined from the isothermal annealing of double-faulted dislocation loops in the electron microscope and found to be 30% greater than the intrinsic energy. The observed rarity of extrinsic faulting in thin foils is accounted for in terms of a nucleation barrier to the formation of an extrinsic fault. Several previous observations of extrinsic faults, some of which have been taken to imply a higher extrinsic stacking-fault energy, are re-examined in the light of this barrier.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"11 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":"132735326","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: 10.1179/030634573790445361
M. Vowles, J. Billingham, E. Culpan
AbstractThe magnetic permeability of a series of complex, high-strength cupro-nickel alloys is shown to be strongly dependent on the composition and degree of order of the strengthening γ′ (Ni3Al-type) precipitate. Electron metallography and X-ray-diffraction techniques were used to study the precipitation occurring in such alloys in the quenched, slowly cooled, and aged conditions. The composition of the γ′ precipitate varied with both alloy content and heat-treatment but was of the general form (NiCuh)3(AlFeMn). The effect of precipitate composition and degree of order on magnetic permeability was examined in a number of synthetic alloys with compositions similar to those of precipitates extracted from the original alloys. A direct correlation of magnetic permeability with the ordered state of these precipitates was possible by means of dark-field microscopy. The alloys have high magnetic permeability when ordered ferromagnetic precipitates are formed within a limited composition range. Magnetic permeab...
{"title":"Correlation of Magnetic Permeability and Microstructure in Cupro-Nickel Alloys","authors":"M. Vowles, J. Billingham, E. Culpan","doi":"10.1179/030634573790445361","DOIUrl":"https://doi.org/10.1179/030634573790445361","url":null,"abstract":"AbstractThe magnetic permeability of a series of complex, high-strength cupro-nickel alloys is shown to be strongly dependent on the composition and degree of order of the strengthening γ′ (Ni3Al-type) precipitate. Electron metallography and X-ray-diffraction techniques were used to study the precipitation occurring in such alloys in the quenched, slowly cooled, and aged conditions. The composition of the γ′ precipitate varied with both alloy content and heat-treatment but was of the general form (NiCuh)3(AlFeMn). The effect of precipitate composition and degree of order on magnetic permeability was examined in a number of synthetic alloys with compositions similar to those of precipitates extracted from the original alloys. A direct correlation of magnetic permeability with the ordered state of these precipitates was possible by means of dark-field microscopy. The alloys have high magnetic permeability when ordered ferromagnetic precipitates are formed within a limited composition range. Magnetic permeab...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"226 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":"131675652","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.1969.3.1.190
R. Haynes, P. Maddocks
Abstract True stress/true strain curves have been determined for two fine-grained (α + β) titanium alloys containing various amounts of hydrogen, which was present either in solid solution or in solid solution and as a film-like hydride precipitate. In hydride-free specimens three stages, with high, low, and intermediate work-hardening exponents, are identified in the work-hardening of the alloys. The three stages, in order of occurrence, are attributed to partial plastic deformation, easy glide, and parabolic hardening. The presence of hydride lowers the initial flow stress, extends the first stage, eliminates the second stage, and lowers the work-hardening exponent of the third stage of work-hardening. These changes are believed to be caused by the hydride particles acting as stress concentrators, thus enabling localized plastic deformation to occur at low macroscopic stress levels and inducing complex slip at an early stage in work-hardening. Hydride precipitate also causes loss of ductility by markedl...
{"title":"The Effect of Hydrogen on the Work-Hardening and Fracture Behaviour of Titanium–Low-Aluminium–Low-Manganese Alloys","authors":"R. Haynes, P. Maddocks","doi":"10.1179/MSC.1969.3.1.190","DOIUrl":"https://doi.org/10.1179/MSC.1969.3.1.190","url":null,"abstract":"Abstract True stress/true strain curves have been determined for two fine-grained (α + β) titanium alloys containing various amounts of hydrogen, which was present either in solid solution or in solid solution and as a film-like hydride precipitate. In hydride-free specimens three stages, with high, low, and intermediate work-hardening exponents, are identified in the work-hardening of the alloys. The three stages, in order of occurrence, are attributed to partial plastic deformation, easy glide, and parabolic hardening. The presence of hydride lowers the initial flow stress, extends the first stage, eliminates the second stage, and lowers the work-hardening exponent of the third stage of work-hardening. These changes are believed to be caused by the hydride particles acting as stress concentrators, thus enabling localized plastic deformation to occur at low macroscopic stress levels and inducing complex slip at an early stage in work-hardening. Hydride precipitate also causes loss of ductility by markedl...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"16 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131859227","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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