Microstructural extremes and the transition from fatigue crack initiation to small crack growth in a polycrystalline nickel-base superalloy

Miao, Jr‐Ming; Pollock, Tresa M.; Jones, J. W.

doi:10.1016/j.actamat.2012.01.049

Cited by 167 publications

(73 citation statements)

References 30 publications

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“…It is also worth noting that in addition to revealing the deformed layer, the misorientation maps obtained from EBSD reveal that significant deformation are present further below the surface around carbides or twin boundaries. This is a confirmation of the particularities of these microstructures which are known to accumulate deformation in a strain field which will become potential fatigue nucleation sites [25][26][27].…”

Section: Quantification and Validation With Ebsd Misorientation Mapsmentioning

confidence: 76%

Accurate determination of damaged subsurface layers in machined Inconel 718

Touazine

Jahazi

Bocher

2016

Int J Adv Manuf Technol

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The machining of high strength materials used in aeronautical applications generates damage on the subsurface layer which can significantly affect the fatigue life of the machined components. It is then important to distinguish between the damages due to machining from those caused by mechanical polishing operations used for sample observation. In this study, a new method is proposed to characterize and quantify properly the affected layer by machining and eliminate the impact from the defects originated during mechanical polishing. A protective layer of nickel coating was deposited on the machined surface. An optimum thickness of 100 µm was determined for the nickel layer to avoid any damage to the subsurface layer during sample preparation. The subsurface layer was analyzed using an automatic Knoop microhardness machine, laser-digital microscope and Electron BackScatter Diffraction (EBSD) microscopy.

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Section: Quantification and Validation With Ebsd Misorientation Mapsmentioning

confidence: 76%

Accurate determination of damaged subsurface layers in machined Inconel 718

Touazine

Jahazi

Bocher

2016

Int J Adv Manuf Technol

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“…New statistical approaches to sampling large data sets, including the statistics of extremes, are needed in conjunction with careful consideration of the representative volume element required for any given property-perhaps best referred to as the ''property volume element'' (RVE). 41,42 Such considerations will undoubtedly drive the development of new instruments, expand the functionality of existing 3-D characterization approaches, and motivate advances in modeling of composition and structure evolution, as noted in the previous section. A related issue is the level of information that should be retained about 3-D structure for any given material because, in principle, a new design scenario could always change the RVE.…”

Section: The Science Base For Property Prediction Across Length Scalesmentioning

confidence: 99%

Emerging Science and Research Opportunities for Metals and Metallic Nanostructures

Handwerker

Pollock

2014

JOM

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During the next decade, fundamental research on metals and metallic nanostructures (MMNs) has the potential to continue transforming metals science into innovative materials, devices, and systems. A workshop to identify emerging and potentially transformative research areas in MMNs was held June 13 and 14, 2012, at the University of California Santa Barbara. There were 47 attendees at the workshop (listed in the Acknowledgements section), representing a broad range of academic institutions, industry, and government laboratories. The metals and metallic nanostructures (MMNs) workshop aimed to identify significant research trends, scientific fundamentals, and recent breakthroughs that can enable new or enhanced MMN performance, either alone or in a more complex materials system, for a wide range of applications. Additionally, the role that MMN research can play in high-priority research and development (R&D) areas such as the U.S. Materials Genome Initiative, the National Nanotechnology Initiative, the Advanced Manufacturing Initiative, and other similar initiatives that exist internationally was assessed. The workshop also addressed critical issues related to materials research instrumentation and the cyberinfrastructure for materials science research and education, as well as science, technology, engineering, and mathematics (STEM) workforce development, with emphasis on the United States but with an appreciation that similar challenges and opportunities for the materials community exist internationally. A central theme of the workshop was that research in MMNs has provided and will continue to provide societal benefits through the integration of experiment, theory, and simulation to link atomistic, nanoscale, microscale, and mesoscale phenomena across time scales for an ever-widening range of applications. Within this overarching theme, the workshop participants identified emerging research opportunities that are categorized and described in more detail in the following sections in terms of the following: three-dimensional (3-D) and fourdimensional (4-D) materials science. Structure evolution and the challenge of heterogeneous and multicomponent systems. The science base for property prediction across the length scales. Nanoscale phenomena at surfaces-experiment, theory, and simulation. Prediction and control of the morphology, microstructure, and properties of ''bulk'' nanostructured metals. Functionality and control of materials far from equilibrium. Hybrid and multifunctional materials assemblies. Materials discovery and design: enhancing the theory-simulation-experiment loop. Following an introduction, these emerging research opportunities are discussed in detail, along with challenges and opportunities for the materials community in the areas of instrumentation, cyberinfrastructure, education, and workforce development.

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“…Generally, the predetermined tolerance angle is between 3 and 12.5° [29]. The tolerance angle of 5° here was chosen in order to avoid the overlapping of the grain groups in this case, which could be derived from the propagation of some cracks beyond the initiating grains [30]. Since the point-to-point misorientation is often small it is sometimes difficult to discriminate the actual misorientation from the measured orientations, which has an error associated with it of 0.5-1° [31].…”

Section: Analytical Proceduresmentioning

confidence: 99%

Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD

Jiang

Zhao

et al. 2015

Surface and Coatings Technology

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Q. (2015). Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD. Surface and Coatings Technology, Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD AbstractThis work presents a fine microstructure and local misorientation study of various oxide phases in the tertiary oxide scale formed on a hot-rolled steel strip via electron back-scattering diffraction (EBSD). Local strain in individual grains of four phases, ferrite (α-Fe), wustite (FeO), magnetite (Fe 3 O 4 ) and hematite (α-Fe 2 O 3 ), has been systematically analysed. The results reveal that Fe 3 O 4 has a lower local strain than α-Fe 2 O 3 , in particular, on the surface and inner layers of the oxide scale. The multiphase oxides along the cracking or α-Fe 2 O 3 penetration generally develop a high local misorientation. Localised stain along the cracks demonstrates that the misorientation tends to be strong near grain boundaries. The high fraction of small Fe 3 O 4 grains accumulate at the oxide-substrate interface, which leads to a dramatic increase in the intensity of local stain. This variation is due mainly to the phase transformation among the oxide phases, i.e., the Fe 3 O 4 particles during their nucleation and growth. The combined action of stress relief and re-oxidisation is proposed to explain the formation of Fe 3 O 4 seam at the oxide-steel interface. The present study offers an intriguing insight into the deformation behaviour of the tertiary oxide scale formed on steels, and may help with understanding the stress-aided oxidation effect of metal alloys. offers an intriguing insight into the deformation behaviour of the tertiary oxide scale formed on steels, and may help with understanding the stress-aided oxidation effect of metal alloys.

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Microstructural extremes and the transition from fatigue crack initiation to small crack growth in a polycrystalline nickel-base superalloy

Cited by 167 publications

References 30 publications

Accurate determination of damaged subsurface layers in machined Inconel 718

Accurate determination of damaged subsurface layers in machined Inconel 718

Emerging Science and Research Opportunities for Metals and Metallic Nanostructures

Local strain analysis of the tertiary oxide scale formed on a hot-rolled steel strip via EBSD

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