Shearing of γ’ particles in Co-base and Co-Ni-base superalloys

Feng, Longsheng; Lv, Duchao; Rhein, Robert K.; Goiri, Jon Gabriel; Titus, Michael S.; Ven, Anton Van der; Pollock, Tresa M.; Wang, Y.

doi:10.1016/j.actamat.2018.09.013

Cited by 51 publications

(14 citation statements)

References 43 publications

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“…To validate fault energy assessments and understand the complex precipitate shearing mechanisms observed across individual and groups of precipitates following mechanical testing, ab-initio calculations of the generalized-stacking-fault (GSF) potential energy were used for phase field dislocation calculations 41,42 .…”

Section: Resultsmentioning

confidence: 99%

A defect-resistant Co–Ni superalloy for 3D printing

et al. 2020

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Additive manufacturing promises a major transformation of the production of high economic value metallic materials, enabling innovative, geometrically complex designs with minimal material waste. The overarching challenge is to design alloys that are compatible with the unique additive processing conditions while maintaining material properties sufficient for the challenging environments encountered in energy, space, and nuclear applications. Here we describe a class of high strength, defect-resistant 3D printable superalloys containing approximately equal parts of Co and Ni along with Al, Cr, Ta and W that possess strengths in excess of 1.1 GPa in as-printed and post-processed forms and tensile ductilities of greater than 13% at room temperature. These alloys are amenable to crack-free 3D printing via electron beam melting (EBM) with preheat as well as selective laser melting (SLM) with limited preheat. Alloy design principles are described along with the structure and properties of EBM and SLM CoNi-base materials.

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Section: Resultsmentioning

confidence: 99%

A defect-resistant Co–Ni superalloy for 3D printing

et al. 2020

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“…The design tools include density functional theory (VASP), cluster-assisted statistical mechanics (CASM), phase field dislocation dynamics, Calphad calculations, ion-plasma deposition combinatorial libraries, and high-throughput analyses of oxide formation during high-temperature exposure. [130][131][132][133][134][135][136] Use of these tools enabled the large potential design space to be explored efficiently and in a non-linear manner, based upon design goals.…”

Section: Approachmentioning

confidence: 99%

“…[128] The full generalized stacking fault (GSF) surface was also calculated to study dislocation mechanisms in more detail by phase field dislocation calculations to further adjust composition. [136] A Calphad database was also developed [135] and subsequently incorporated into the CompuTherm PanCobalt database. Thermodynamic calculations were used to tune the Ni content to increase the L1 2 solvus temperature to the desired range, and to predict phases present across composition space in the combinatorial studies.…”

Section: Approachmentioning

confidence: 99%

Design and Tailoring of Alloys for Additive Manufacturing

Pollock

Clarke

Babu

2020

Metall Mater Trans A

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Additive manufacturing (AM) promises a major transformation for manufacturing of metallic components for aerospace, medical, nuclear, and energy applications. This perspective paper addresses some of the opportunities for alloy and feedstock design to achieve site-specific and enhanced properties not attainable by conventional manufacturing processes. This paper provides a brief overview of the role of powders, as well as solidification and solid-state phase transformation phenomena typically encountered during fusion-based AM. Three case studies are discussed that leverage the above to arrive at microstructure control. The first case study focuses on approaches to modify the solidification characteristics by in-situ alloying. The second case study focuses on the need for concurrent design of alloys and processing conditions to arrive at the columnar to equiaxed transition during solidification. The third case study focuses on the design of a cobalt alloy for AM, with emphasis on tailoring liquid and solid state phase transformations. The need for comprehensive knowledge of processing conditions during AM, in-situ and ex-situ probing of microstructure development under AM conditions, and post-print processing, characterization, and qualification are articulated for the design of future alloys and component geometries built by AM.

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“…Calculations were performed at the Imperial College Research Computing Service, doi:10.14469/hpc/2232. Tables 2,(1−3 [74] 560 [13] 120 [13] -95 [13] Co 3 Ti 3.575 245 367 239 3.601 [73] 3.572 [75] 208 [75] Co [75] 1190 [13] 658 [13] -132 [13] [73] 223 [47] 172 [47] 79 [47] 3.572 (E) [77] 187 [72] 172 [72] 37 [72] Ni…”

Section: Acknowledgementsmentioning

confidence: 99%

“…This concept has been successfully applied to Ni-based superalloys [10,11,12] to study the mechanisms of creep and yield. While, there has been an attempt to create a PFMD description of Co-based superalloys by Feng et al [13], the authors did not employ a complete first-principles Γ-surface for Co 3 (Al,W) γ phase. Instead, the study relied on an interpolation of binary L1 2 -ordered Co 3 Al and Co 3 W fault energy data and experimentally obtained values.…”

Section: Introductionmentioning

confidence: 99%

Generalised stacking fault energy of Ni-Al and Co-Al-W superalloys: Density-functional theory calculations

et al. 2020

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Generalised stacking fault energy surfaces (Γ-surfaces) are calculated for CoAl -W-based and Ni-Al-based superalloys from first-principles calculations. A Special Quasi-random Structure is employed in the calculation of the ternary compound, Co 3 (Al,W). Phase field simulations are used to compare dislocation cores present in Co-based and Ni-based superalloys. The higher planar fault energies of the Co-based system lead to a more constricted dislocation which can have implications on both the bowing of dislocations as well as cross-slip. Additionally, planar fault energies of various L1 2 compounds are compared to explain observed segregation pathways in both types of superalloy. Both the planar fault energies and the segregation pathways are discussed within the context of strengthening mechanisms in superalloys.

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Shearing of γ’ particles in Co-base and Co-Ni-base superalloys

Cited by 51 publications

References 43 publications

A defect-resistant Co–Ni superalloy for 3D printing

A defect-resistant Co–Ni superalloy for 3D printing

Design and Tailoring of Alloys for Additive Manufacturing

Generalised stacking fault energy of Ni-Al and Co-Al-W superalloys: Density-functional theory calculations

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