AbstractThe effect of variations in alloy composition, quench rate, and deformation on the formation of FPP (Frank partial precipitation) has been studied by means of hardness measurements and electron microscopy. Solute concentration is the most important factor controlling the maximum area of FPP. The numbers of precipitate particles increase with dislocation density but the number per unit length of dislocation is generally lower the higher is the dislocation density. The efficiency of nucleation by a dislocation is therefore not increased by the prior cold work and this is consistent with nucleation by climbed loops. The free-vacancy profile near grain boundaries is used to explain the FPP-free zone (PFZ) width, and this is controlled by the rate of precipitation. Silicon additions accelerate the nucleation of NbC and promote FPP formation.
{"title":"Factors Affecting the Precipitation of NbC on Frank Partial Dislocations in Fe–Ni–16% Cr Austenitic Steels","authors":"J. Silcock, K. W. Sidding, T. Fry","doi":"10.1179/MSC.1970.4.1.29","DOIUrl":"https://doi.org/10.1179/MSC.1970.4.1.29","url":null,"abstract":"AbstractThe effect of variations in alloy composition, quench rate, and deformation on the formation of FPP (Frank partial precipitation) has been studied by means of hardness measurements and electron microscopy. Solute concentration is the most important factor controlling the maximum area of FPP. The numbers of precipitate particles increase with dislocation density but the number per unit length of dislocation is generally lower the higher is the dislocation density. The efficiency of nucleation by a dislocation is therefore not increased by the prior cold work and this is consistent with nucleation by climbed loops. The free-vacancy profile near grain boundaries is used to explain the FPP-free zone (PFZ) width, and this is controlled by the rate of precipitation. Silicon additions accelerate the nucleation of NbC and promote FPP formation.","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":"115058111","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: 10.1179/030634572790445984
L. C. E. Geniets, J. F. Knottt
AbstractConventional measurements of the degree of temperembrittlement suffered by a steel are made in terms of the shift of the notched-bar “fracture appearance” transition temperatures (FATT). Any fundamental explanation of temperembrittlement must be concerned with the lowering of grain-boundary cohesion by the segregation of impurity. elements to grain boundaries over a critical temperature range, typically 560–430° C. The use of transition shifts to estimate the kinetics of reduction of grain-boundary cohesion can be criticized on several counts. First, it is often the case that the unembrittled condition breaks by cleavage rather than by intergranular fracture at low temperatures, so that no measure of the unembrittled grain-boundary cohesion can be obtained. Secondly, even if both fractures are intergranular, the shift compares fracture events at different temperatures and there is no guarantee that the relative grain-boundary cohesive strengths do not change with temperature. Thirdly, the temper-b...
{"title":"Grain-Boundary Segregation and Temper-Brittle Fracture in a Low-Alloy Steel","authors":"L. C. E. Geniets, J. F. Knottt","doi":"10.1179/030634572790445984","DOIUrl":"https://doi.org/10.1179/030634572790445984","url":null,"abstract":"AbstractConventional measurements of the degree of temperembrittlement suffered by a steel are made in terms of the shift of the notched-bar “fracture appearance” transition temperatures (FATT). Any fundamental explanation of temperembrittlement must be concerned with the lowering of grain-boundary cohesion by the segregation of impurity. elements to grain boundaries over a critical temperature range, typically 560–430° C. The use of transition shifts to estimate the kinetics of reduction of grain-boundary cohesion can be criticized on several counts. First, it is often the case that the unembrittled condition breaks by cleavage rather than by intergranular fracture at low temperatures, so that no measure of the unembrittled grain-boundary cohesion can be obtained. Secondly, even if both fractures are intergranular, the shift compares fracture events at different temperatures and there is no guarantee that the relative grain-boundary cohesive strengths do not change with temperature. Thirdly, the temper-b...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"38 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":"115057527","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: 10.1179/030634572790446037
T. Williams
AbstractThe boron autoradiography techniques, using optical and electron microscopy, developed at the Atomic Energy Research Establishment, Harwell, have been described in some detail in two publications by Hughes et al. The present paper illustrates the usefulness of the techniques in the study of the effects of boron on the properties of Type-316 stainless steel.
{"title":"The Segregation and Effects of Boron in an Austenitic Stainless Steel","authors":"T. Williams","doi":"10.1179/030634572790446037","DOIUrl":"https://doi.org/10.1179/030634572790446037","url":null,"abstract":"AbstractThe boron autoradiography techniques, using optical and electron microscopy, developed at the Atomic Energy Research Establishment, Harwell, have been described in some detail in two publications by Hughes et al. The present paper illustrates the usefulness of the techniques in the study of the effects of boron on the properties of Type-316 stainless steel.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"16 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":"123388784","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: 10.1179/030634568790443288
S. R. Anthony, J. Congleton
Abstract The phenomenon of crack branching in metals is discussed in terms of KB, the elastic stress intensity at the crack tip when crack branching occurs. It is shown that KB measurements may be useful in determining the fracture toughness of brittle metals.
{"title":"Crack Branching in Strong Metals","authors":"S. R. Anthony, J. Congleton","doi":"10.1179/030634568790443288","DOIUrl":"https://doi.org/10.1179/030634568790443288","url":null,"abstract":"Abstract The phenomenon of crack branching in metals is discussed in terms of KB, the elastic stress intensity at the crack tip when crack branching occurs. It is shown that KB measurements may be useful in determining the fracture toughness of brittle metals.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"76 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":"114699496","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: 10.1179/030634572790445975
B. Noble, G. Thompson
Abstract T 1 precipitation has been studied by electron microscopy in aluminium alloys containing (wt.-%) Cu 3.5, Li 1.5 and Cu 2.5, Li 2.0. The T 1 phase forms as extremely thin hexagonal-shaped plates with a {111} habit plane and, depending on the degree of super-saturation, nucleates either at GP zones or at dissociated dislocations by a stacking-fault mechanism. The precipitate is bounded by 1/6 Shockley partial dislocations and growth of the phase occurs by separation of these partial dislocations.
摘要:用电镜研究了(wt.-%) Cu 3.5, Li 1.5和Cu 2.5, Li 2.0铝合金中的t1析出。t1相形成极薄的六边形板，具有{111}习惯面，并且根据过饱和程度，在GP带或通过堆叠-断层机制在解离位错处成核。析出相以1/6肖克利部分位错为界，这些部分位错的分离使相长大。
{"title":"T 1 (Al2CuLi) Precipitation in Aluminium–Copper–Lithium Alloys","authors":"B. Noble, G. Thompson","doi":"10.1179/030634572790445975","DOIUrl":"https://doi.org/10.1179/030634572790445975","url":null,"abstract":"Abstract T 1 precipitation has been studied by electron microscopy in aluminium alloys containing (wt.-%) Cu 3.5, Li 1.5 and Cu 2.5, Li 2.0. The T 1 phase forms as extremely thin hexagonal-shaped plates with a {111} habit plane and, depending on the degree of super-saturation, nucleates either at GP zones or at dissociated dislocations by a stacking-fault mechanism. The precipitate is bounded by 1/6 Shockley partial dislocations and growth of the phase occurs by separation of these partial dislocations.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"175 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":"123839740","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}
Pub Date : 1900-01-01DOI: 10.1179/MSC.1970.4.1.222
H. B. Aaron, G. Kotler
AbstractThe effects of curvature on the dissolution kinetics of spherical precipitates is investigated. This is accomplished by using a modified Gibbs–Thompson equation to represent the composition in the matrix at the precipitate/matrix interface as a function of precipitate radius. In this way one can account for the increasing curvature of the dissolving precipitate. The range of physical parameters for which the effect of curvature may appreciably alter the kinetics of diffusion-controlled dissolution is discussed. The presence of curvature tends to speed up dissolution, being particularly important at long times (i.e., small precipitate sizes) and when the difference between the solute concentration at the precipitate/matrix interface (Cr I ) and in the depleted matrix (C M ) is small. It is shown, however, that curvature will, in general, not sensibly affect the dissolution kinetics even at long times unless the concentration difference (Cr I – C M ) is sufficiently small.
摘要研究了曲率对球形析出物溶解动力学的影响。这是通过使用改进的Gibbs-Thompson方程来实现的，该方程将析出物/基体界面处的基体成分表示为析出物半径的函数。这样就可以解释溶解沉淀物曲率的增加。讨论了曲率影响可能显著改变扩散控制溶解动力学的物理参数范围。曲率的存在倾向于加速溶解，这在时间长(即析出物尺寸小)和析出物/基体界面(Cr I)和耗尽基体(cm)的溶质浓度差很小的情况下尤为重要。然而，一般来说，曲率即使在很长时间内也不会明显影响溶解动力学，除非浓度差(Cr I - cm)足够小。
{"title":"The Effects of Curvature on the Dissolution Kinetics of Spherical Precipitates","authors":"H. B. Aaron, G. Kotler","doi":"10.1179/MSC.1970.4.1.222","DOIUrl":"https://doi.org/10.1179/MSC.1970.4.1.222","url":null,"abstract":"AbstractThe effects of curvature on the dissolution kinetics of spherical precipitates is investigated. This is accomplished by using a modified Gibbs–Thompson equation to represent the composition in the matrix at the precipitate/matrix interface as a function of precipitate radius. In this way one can account for the increasing curvature of the dissolving precipitate. The range of physical parameters for which the effect of curvature may appreciably alter the kinetics of diffusion-controlled dissolution is discussed. The presence of curvature tends to speed up dissolution, being particularly important at long times (i.e., small precipitate sizes) and when the difference between the solute concentration at the precipitate/matrix interface (Cr I ) and in the depleted matrix (C M ) is small. It is shown, however, that curvature will, in general, not sensibly affect the dissolution kinetics even at long times unless the concentration difference (Cr I – C M ) is sufficiently small.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"127 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":"128901597","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}
AbstractTensile tests and transmission electron microscopy have been used to investigate the relationship between mechanical properties and microstructure in three plain carbon steels shock-loaded to peak pressures between 100 and 250 kilobars. The most dramatic change in structures and properties occurs at pressures in excess of that required to induce the phase transformation α → ɛ → α. The value of this pressure depends on the original microstructure of the steel, so that an annealed low-carbon steel shows considerable transformation at 150 kilobars, while a normalized 0.99% C steel does not transform until the peak pressure exceeds 200 kilobars. Below the transformation pressure the low-carbon steel is strengthened by shock-loading, while this does not occur in the two high-carbon steels.
{"title":"The Structure and Mechanical Properties of Shock-Loaded Steels","authors":"H. Bowden, P. Kelly","doi":"10.1179/MSC.1967.1.1.75","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.75","url":null,"abstract":"AbstractTensile tests and transmission electron microscopy have been used to investigate the relationship between mechanical properties and microstructure in three plain carbon steels shock-loaded to peak pressures between 100 and 250 kilobars. The most dramatic change in structures and properties occurs at pressures in excess of that required to induce the phase transformation α → ɛ → α. The value of this pressure depends on the original microstructure of the steel, so that an annealed low-carbon steel shows considerable transformation at 150 kilobars, while a normalized 0.99% C steel does not transform until the peak pressure exceeds 200 kilobars. Below the transformation pressure the low-carbon steel is strengthened by shock-loading, while this does not occur in the two high-carbon steels.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"29 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":"122500531","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: 10.1179/030634572790446028
C. M. Wayman, K. Shimizu
AbstractThe shape memory effect, by which a material, apparently plastically deformed, reverts to its original shape upon heating to some higher temperature, has been reviewed and discussed from the point of view of the crystallography of martensitic transformations. Considering the general characteristics of martensitic materials that exhibit the shape memory behaviour, some phenomena peculiar to the prototype NiTi alloy are shown to have no direct relation to the shape memory. It is concluded that the shape memory effect can be universally correlated with a martensitic transformation that is thermoelastic in nature, the thermoelasticity being attributed to ordering in the parent and martensitic phases.Prerequisites for the shape memory behaviour are suggested to be: (1) that the martensitic transformation is thermoelastic; (2) that the parent and martensitic phases are ordered; and (3) that the martensite is internally twinned. The low-temperature deformation process is discussed with reference to the l...
{"title":"The Shape Memory (‘Marmem’) Effect in Alloys","authors":"C. M. Wayman, K. Shimizu","doi":"10.1179/030634572790446028","DOIUrl":"https://doi.org/10.1179/030634572790446028","url":null,"abstract":"AbstractThe shape memory effect, by which a material, apparently plastically deformed, reverts to its original shape upon heating to some higher temperature, has been reviewed and discussed from the point of view of the crystallography of martensitic transformations. Considering the general characteristics of martensitic materials that exhibit the shape memory behaviour, some phenomena peculiar to the prototype NiTi alloy are shown to have no direct relation to the shape memory. It is concluded that the shape memory effect can be universally correlated with a martensitic transformation that is thermoelastic in nature, the thermoelasticity being attributed to ordering in the parent and martensitic phases.Prerequisites for the shape memory behaviour are suggested to be: (1) that the martensitic transformation is thermoelastic; (2) that the parent and martensitic phases are ordered; and (3) that the martensite is internally twinned. The low-temperature deformation process is discussed with reference to the l...","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":"122601345","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: 10.1179/030634573790445307
W. Yang, R. Dodd
Abstract The high- and intermediate-temperature creep properties of NiAl are quite sensitive to deviations from stoichiometry, although the creep always appears to be diffusion-controlled. The unusual dislocation micro-structures in Al-rich NiAl and the demonstrated influence of impurities in stoichiometric NiAl preclude a straightforward analysis of intrinsic rate-determining mechanisms.
{"title":"Steady-State Creep and Associated Microstructures in Stoichiometric and Non-Stoichiometric Polycrystalline NiAl","authors":"W. Yang, R. Dodd","doi":"10.1179/030634573790445307","DOIUrl":"https://doi.org/10.1179/030634573790445307","url":null,"abstract":"Abstract The high- and intermediate-temperature creep properties of NiAl are quite sensitive to deviations from stoichiometry, although the creep always appears to be diffusion-controlled. The unusual dislocation micro-structures in Al-rich NiAl and the demonstrated influence of impurities in stoichiometric NiAl preclude a straightforward analysis of intrinsic rate-determining mechanisms.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"41 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":"126138762","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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