Microstructural statistics for fatigue crack initiation in polycrystalline nickel-base superalloys

Stinville, J.C.; Lenthe, William C.; Echlin, McLean P.; Callahan, Patrick G.; Texier, Damien; Pollock, Tresa M.

doi:10.1007/s10704-017-0241-z

Cited by 72 publications

(33 citation statements)

References 53 publications

(91 reference statements)

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“…The difficulty of assessing such local irreversible deformation at the microscale lies within the capability to observe and measure small displacements induced by the deformation mechanisms, including slip localization and deformation twinning [3e7]. Slip localization was found to develop in grains favorably oriented for slip activity in fcc materials (high Schmid factor (SF)) [8e10] or in the vicinity of and parallel to twin boundaries presenting either a high Schmid factor or a significant difference in elastic properties between the twin and the parent grain [2,3,11]. Such local and intense strain localization befalls at macroscopic stresses significantly below the yield strength of the material and degrades its fatigue life under cyclic loading.…”

Section: In-plane and Out-of-plane Deformation At The Sub-grain Scalementioning

confidence: 99%

“…This qualitative slip characterization is incapable of quantifying the displacement amplitude associated with individual slip bands nor the in-plane/ out-of-plane gliding direction. While complementary ex-situ atomic force microscopy (AFM) observations aim to quantitatively investigate the out-of-plane intensity of the slip band emergence and/or extrusions [8,14], the timeliness of this nanoscale characterization technique is not suitable for the investigation of nearlymillimeter-squared regions of interest, required for the statistical study of crystal plasticity in tens-of-micrometer grain size materials [3]. Therefore, alternative solutions are needed for the quantitative and statistical assessment of slip localization, i.e.…”

Section: In-plane and Out-of-plane Deformation At The Sub-grain Scalementioning

confidence: 99%

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In-plane and out-of-plane deformation at the sub-grain scale in polycrystalline materials assessed by confocal microscopy

et al. 2019

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a b s t r a c tHigh-resolution digital image correlation (HR-DIC) techniques have become essential in material mechanics to assess strain measurements at the scale of the elementary mechanisms responsible of the deformation in polycrystalline materials. The purpose of this study is to demonstrate the use of laser scanning confocal microscopy (LSCM) coupled with DIC techniques to deepen knowledge on the deformation process of a polycrystalline nickel-based superalloy at room temperature. The LSCM technique is capable of detecting both in-plane and out-of-plane strain localization within slip bands at the sub-grain level. The LSCM observations are consistent with previous in-situ scanning electron microscopy (SEM) studies: The onset of crystal plasticity occurs primarily near S3 twin boundaries with macroscopic loading in the elastic domain (macroscopic stress as low as 80% of the 0.2% offset yield strength (Y.S. 0.2% )). This intense irreversible strain localization occurs with either a high Schmid factor (m > 0.43) or a significant elastic modulus difference between the pair of twins (DЕ > 100 GPa). In the plastic deformation domain, transgranular slip activity following slip systems with the highest Schmid factor is mostly responsible for the deformation at the grain level, thus leading to strain percolation. The simultaneous in-plane and out-of-plane deformation assessment via the HR-LSCM-DIC technique was found to be essential for the identification of active slip systems. Finally, the HR-LSCM-DIC technique enabled the quantification of the glide amplitude involved in the three-dimensional shearing process at the grain level that solely in-plane measurements cannot provide.

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Section: In-plane and Out-of-plane Deformation At The Sub-grain Scalementioning

confidence: 99%

Section: In-plane and Out-of-plane Deformation At The Sub-grain Scalementioning

confidence: 99%

In-plane and out-of-plane deformation at the sub-grain scale in polycrystalline materials assessed by confocal microscopy

et al. 2019

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“…82 Lab-scale x-ray tomography and ever-expanding synchrotron beamline facilities are revolutionizing our ability to collect 3D and 4D data. [83][84][85][86] In cases where higher resolution information about chemistry or microstructure is required, automated serial sectioning systems [87][88][89][90][91][92][93] can now collect such The 3D data set for a polycrystalline nickel-based superalloy (Figure 3b, center) was collected by the femtosecond laserassisted TriBeam tomography approach in 132 h. [94][95][96] The specific motivation for this data set was to extract 3D information on grain size and orientation and the connectivity of twinrelated grains, shown in a network representation (Figure 3b, bottom) for prediction of strength and fatigue behavior. [95][96][97]…”

Section: In Situ 3d and 4d Microscopymentioning

confidence: 99%

“…97 Properties such as fatigue crack initiation life converges at a higher volume element size of 500 μm 3 . 94,95 While this is only one example of the characterization capability developed to support modeling, future close coupling between models and characterization will dramatically improve predictive capabilities across a spectrum of properties.…”

Section: Model-driven Characterizationmentioning

confidence: 99%

The evolving landscape for alloy design

Pollock

Ven

2019

MRS Bull.

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“…Slip transfer across grain boundaries enables long-range shear bands to form (Abuzaid et al, 2016), which affect the length of eventual fatigue crack formation, and also can lead to twin formation (Wang et al, 2010;Eftink et al, 2017). Moreover, slip localization parallel to annealing twins can lead to a preferential site for fatigue crack nucleation in Nibased superalloys (Stinville et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

An analysis of (the lack of) slip transfer between near-cube oriented grains in pure Al

Bieler

Alizadeh

Peña-Ortega

et al. 2019

International Journal of Plasticity

114

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Slip transfer across grain boundaries was studied in annealed polycrystalline Al foils deformed in uniaxial tension by means of the analysis of the slip traces on the specimen surface. Grain orientations and selected grain boundary misorientations were measured on both surfaces of the sample using electron back-scattered diffraction mapping. It was found that most of the grains were within 15° of a cube orientation and approximately half of the grains percolated through the specimen thickness. The Luster-Morris " parameter (that can be computed from the surface grain orientation) was used to assess the likelihood of slip transfer across boundaries. It was found that transfer across grain boundaries was rare in near-cube oriented grains, and convincing evidence was only found when " > 0.97, which corresponds to lowangle boundaries with <15º misorientation. This behavior was explained by the presence of many active slip slips in near-cube oriented grains that favor self-accommodation of the grain shape to the evolving boundary conditions imposed by neighboring grains instead of promoting slip transfer across the boundary. These results indicate that the alignment between slip planes and slip directions across the boundary is not the only important metric to determine the threshold for slip transfer, as the particular details of deformation in each grain (such as the number of available slip systems) also must be considered.

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Microstructural statistics for fatigue crack initiation in polycrystalline nickel-base superalloys

Cited by 72 publications

References 53 publications

In-plane and out-of-plane deformation at the sub-grain scale in polycrystalline materials assessed by confocal microscopy

In-plane and out-of-plane deformation at the sub-grain scale in polycrystalline materials assessed by confocal microscopy

The evolving landscape for alloy design

An analysis of (the lack of) slip transfer between near-cube oriented grains in pure Al

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