Dislocation decorrelation and relationship to deformation microtwins during creep of a γ′ precipitate strengthened Ni-based superalloy

Unocic, Raymond R.; Zhou, Ning; Kovařík, Libor; Chen, Shen; Mills, Michael J.

doi:10.1016/j.actamat.2011.07.069

Cited by 155 publications

(65 citation statements)

References 36 publications

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“…Cuboidal secondary γ′ size and spacing plays a critical role in determining whether dislocations prefer to stay as a/2<110> type or dissociate into a/6<112> Shockley partials [4]. The cuboidal secondary γ′ size for both standard and serrated microstructures, were determined by sampling more than 450 particles following the methods of Payton et al [20].…”

Section: Methodsmentioning

confidence: 99%

“…Thus, individual channel widths are defined as the segments between particles along the lines connecting the centers of mass (the pixels within the particles are excluded). Second, in order to verify the channel spacing calculated by Delaunay triangulation, Phase Field simulations based on dislocation line tension were used to determine the minimum channel width to achieve dislocation activity for this specific microstructure at the experimentally applied shear stress [4]. Phase Field simulations were set-up so that a dislocation line was placed at the right edge of the simulation cell with either a uniform particle size and spacing (benchmark) or the experimentally determined particle distributions.…”

Section: Methodsmentioning

confidence: 99%

“…Dislocation mechanisms were experimentally observed and compared with mechanism predictions from a Phase Field Dislocation Dynamics model [4]. The propensity for slip transfer versus slip blocking was assessed using the m′ factor.…”

Section: Introductionmentioning

confidence: 99%

“…Phase field simulations allowed for the creation of a Dislocation Activity Diagram (DAD) using the critical channel width [4]. The DAD shows the influence of stress magnitude and orientation on the dislocation dissociation behavior and is illustrated in Figure 6.…”

Section: Dominant Mechanism Observationsmentioning

confidence: 99%

“…Creep deformation in polycrystalline nickel-based superalloys is a heterogeneous process that is primarily a function of γ′ distribution [1][2][3][4], but grain size and orientation also play roles [5,6]. Previous work has explored the effects of grain boundary character on deformation mechanisms, and has concluded that increasing the fraction of special Σn boundaries with n values ranging between 3 and 29, as determined by Coincidence-Site Lattice (CSL) Theory [7], dramatically increases creep, fatigue and corrosion resistance due to a decreased propensity for crack nucleation at Σn boundaries [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Characterization of Strain Accommodation at Grain Boundaries of Nickel-based Superalloys

Carter¹,

Zhou²,

Sosa³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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Elevated temperature in-situ experiments, local crystallographic mapping and digital image correlation techniques have been used to gain insight into strain localization near grain boundaries in polycrystalline René-104. Samples were heat treated to create either smooth (standard) or serrated grain boundaries. Deformation experiments concluded that strain tended to localize at triple points and special boundaries in the standard microstructure, while strain had a less-pronounced correlation in the serrated microstructure. Both materials exhibited grain boundary sliding (GBS), but the standard microstructure proved to be more susceptible. Site-specific extraction of TEM foils indicated that boundaries that exhibited strain localization experienced activation of multiple slip systems, while boundaries showing GBS showed activation of only a single slip system. Based on m′ analysis, slip transmission was expected to be difficult in boundaries that exhibited strain localization while boundaries that showed sliding allowed for easy slip transmission. A volume containing a boundary that exhibited GBS was analyzed to assess boundary surface topography and indicated that the boundary was macroscopically planer with local deviations that were on the order of the secondary γ′ size.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Dominant Mechanism Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Characterization of Strain Accommodation at Grain Boundaries of Nickel-based Superalloys

Carter¹,

Zhou²,

Sosa³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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Grain Scale Crystal Plasticity Model with Slip and Microtwinning for a Third Generation Ni‐Base Disk Alloy

Song

2012

Superalloys 2012

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A relatively simple grain scale crystal plasticity model is developed for the third generation Ni-base disk superalloy ME3. The constitutive model embeds both microtwinning and octahedral and cube slip without explicitly modeling ' precipitates and matrix. The average size and volume fraction of ' precipitates as well as the average grain size and crystallographic orientation are incorporated to embed sub-grain microstructural effects. Additionally, microtwinning is incorporated to specify the slip system shearing rate contribution via an Orowan equation, with kinetics based on diffusional reordering. The constitutive model is calibrated to straincontrolled cyclic histories and constant load creep experimental data for two supersolvus microstructures at 704 • C and 760 • C.

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Deformation Mechanisms Coupled with Phase Field and Crystal Plasticity Modeling in a High‐Temperature Polycrystalline Ni‐Based Superalloy

et al. 2012

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Physics-based modeling of disk superalloys is inherently complex due to the strong influence of microstructure on properties, as well as the multitude of deformation mechanisms operative at elevated temperatures. The present contribution will focus on the effects of monotonic and cyclic loading conditions, and the underlying deformation mechanisms will be discussed. Detailed substructure analysis of deformed specimens was conducted with scanning transmission electron microscopy diffraction-contrast methods. These characterization efforts have led to a series of phase field simulations in which the interaction of various deformation modes with experimentally measured precipitate configurations can be explored and critical parameters quantified. Additionally, these results have been incorporated into a novel, dislocation-densitybased crystal plasticity model that has been calibrated based on a single crystal response, and enables the computationally efficient modeling of polycrystalline behavior.

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Dislocation decorrelation and relationship to deformation microtwins during creep of a γ′ precipitate strengthened Ni-based superalloy

Cited by 155 publications

References 36 publications

Characterization of Strain Accommodation at Grain Boundaries of Nickel-based Superalloys

Characterization of Strain Accommodation at Grain Boundaries of Nickel-based Superalloys

Grain Scale Crystal Plasticity Model with Slip and Microtwinning for a Third Generation Ni‐Base Disk Alloy

Deformation Mechanisms Coupled with Phase Field and Crystal Plasticity Modeling in a High‐Temperature Polycrystalline Ni‐Based Superalloy

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