Creep Behavior of Quinary γ′-Strengthened Co-Based Superalloys

Rhein, Robert K.; Callahan, Patrick G.; Murray, Sean P.; Stinville, J.C.; Titus, Michael S.; Ven, Anton Van der; Pollock, Tresa M.

doi:10.1007/s11661-018-4768-z

Cited by 10 publications

(3 citation statements)

References 32 publications

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“…CASM includes cluster expansions for configurational disorder in multi-component solids and lattice-dynamical effective Hamiltonians for vibrational degrees of freedom involved in structural phase transitions. CASM was used to assess the intrinsic thermodynamic stability of the L1 2 phase at elevated temperatures, to calculate the ternary Co–Al–W phase diagram and to assess the finite temperature fault energies and the driving forces for segregation at planar faults 45 – 47 .…”

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 addition of alloying elements, e.g., Ni, Ta, Ti, Nb, may stabilize the L1 2 phase toward higher temperatures [3][4][5][6]. Substantial effort was done in order to investigate the role of alloying elements in a microstructure and properties of new superalloys [7][8][9][10][11]. Relatively low attention was paid to technological aspects.…”

Section: Introductionmentioning

confidence: 99%

Crystallization behavior of ternary γ–γ′ Co–Al–W alloy

Migas

Gradoń

Mikuszewski

et al. 2020

J Therm Anal Calorim

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In the investigation, crystallization behavior of ternary γ–γ′ alloy based on Co–Al–W system was analyzed. The alloy with nominal composition Co–9Al–9W (at.%) was prepared via vacuum induction melting. Solidification characteristics of the investigated superalloy were obtained by a method of thermal analysis based on temperature measurement of metal solidifying in a mold. After casting, obtained metallic materials were investigated by differential thermal analysis in order to determine characteristic temperatures and compare results with those of obtained in the first thermal analysis. Furthermore, a description of primary microstructure was performed for ingots solidified with two different cooling rates. The analysis was made using X-ray diffraction, optical microscopy and scanning electron microscopy. The crystallization path of alloy was investigated. The solidification range of alloy was narrow. The crystallization in a sand mold resulted in the dendritic microstructure containing γ single phase. The as-cast microstructure after solidification with higher cooling rate was comparable; however, observed crystals were mostly columnar, while sand cast was characterized by equiaxed crystals structure.

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“…In contrast, the effects for Co 3 X (X = Nb, Ta, and Ti) are dramatic. It was suggested that, as a function of temperature, significant amounts of Ta and Nb in γ increase SISF energy, while high amounts of Ti decrease SISF energy (152). Recently, Dodaran et al (135) estimated APB (111) energies in compositions based on the γ phase in Inconel 939.…”

Section: Alloying Effects In Ni- Co- and Coni-base Superalloysmentioning

confidence: 99%

Precipitate Shearing, Fault Energies, and Solute Segregation to Planar Faults in Ni-, CoNi-, and Co-Base Superalloys

Eggeler

Vamsi

Pollock

2021

Annu. Rev. Mater. Res.

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The mechanical properties of superalloys are strongly governed by the resistance to shearing of ordered precipitates by dislocations. In the operating environments of superalloys, the stresses and temperatures present during thermomechanical loading influence the dislocation shearing dynamics, which involve diffusion and segregation processes that result in a diverse array of planar defects in the ordered L12 γ′ precipitate phase. This review discusses the current understanding of high-temperature deformation mechanisms of γ′ precipitates in two-phase Ni-, Co-, and CoNi-base superalloys. The sensitivity of planar fault energies to chemical composition results in a variety of unique deformation mechanisms, and methods to determine fault energies are therefore reviewed. The degree of chemical segregation in the vicinity of planar defects reveals an apparent phase transformation within the parent γ′ phase. The kinetics of segregation to linear and planar defects play a significant role in high-temperature properties. Understanding and controlling fault energies and the associated dislocation dynamics provide a new pathway for the design of superalloys with exceptional properties.

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Creep Behavior of Quinary γ′-Strengthened Co-Based Superalloys

Cited by 10 publications

References 32 publications

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

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

Crystallization behavior of ternary γ–γ′ Co–Al–W alloy

Precipitate Shearing, Fault Energies, and Solute Segregation to Planar Faults in Ni-, CoNi-, and Co-Base Superalloys

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