Amorphous complexions enable a new region of high temperature stability in nanocrystalline Ni-W

Schuler, Jennifer D.; Donaldson, Olivia K.; Rupert, Timothy J.

doi:10.1016/j.scriptamat.2018.05.023

Cited by 52 publications

(25 citation statements)

References 58 publications

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“…This finding is in agreement with previously reported results from a study of a binary Cu-Zr alloy [28,29]. The formation of AIFs has also been achieved in a variety of other metallic alloy systems, such as Mo-Ni [26], Ni-W [52], and Cu-Hf [32], with no abnormal grain growth reported.…”

Section: Microstructural Evolution During Annealingsupporting

confidence: 92%

Thick amorphous complexion formation and extreme thermal stability in ternary nanocrystalline Cu-Zr-Hf alloys

Grigorian

Rupert

2019

Acta Materialia

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Building on the recent discovery of tough nanocrystalline Cu-Zr alloys with amorphous intergranular films, this paper investigates ternary nanocrystalline Cu-Zr-Hf alloys with a focus on understanding how alloy composition affects the formation of disordered complexions. Binary Cu-Zr and Cu-Hf alloys with similar initial grain sizes were also fabricated for comparison. The thermal stability of the nanocrystalline alloys was evaluated by annealing at 950 °C (>95% of the solidus temperatures), followed by detailed characterization of the grain boundary structure. All of the ternary alloys exhibited exceptional thermal stability comparable to that of the binary Cu-Zr alloy, and remained nanocrystalline even after two weeks of annealing at this extremely high temperature. Despite carbide formation and growth in these alloys during milling and annealing, the thermal stability of the ternary alloys is mainly attributed to the formation of thick amorphous intergranular films at high temperatures. Our results show that ternary alloy compositions have thicker boundary films compared to the binary alloys with similar global dopant concentrations.While it is not required for amorphous complexion formation, this work shows that having at least three elements present at the interface can lead to thicker grain boundary films, which is expected to maximize the previously reported toughening effect.

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Section: Microstructural Evolution During Annealingsupporting

confidence: 92%

Thick amorphous complexion formation and extreme thermal stability in ternary nanocrystalline Cu-Zr-Hf alloys

Grigorian

Rupert

2019

Acta Materialia

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“…AIFs strongly resist grain growth, so much that even when nanocrystalline ball milled Cu-Zr containing AIFs was held at 98% of its solidus temperature for a week, it remained nanocrystalline [23]. In fact, Schuler et al [35] even observed a new regime of high temperature nanocrystalline stability due to AIF formation in Ni-W alloys. The ability of AIFs to both stabilize the grain size and diffuse local grain boundary strain concentrations may contribute to the absence of grain coarsening in the AIF-containing sample at fatigue crack nucleation.…”

Section: Resultsmentioning

confidence: 99%

In Situ High-Cycle Fatigue Reveals Importance of Grain Boundary Structure in Nanocrystalline Cu-Zr

Schuler¹,

Barr²,

Heckman³

et al. 2019

JOM

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Nanocrystalline metals typically have high fatigue strengths, but low resistance to crack propagation. Amorphous intergranular films are disordered grain boundary complexions that have been shown to delay crack nucleation and slow crack propagation during monotonic loading by diffusing grain boundary strain concentrations, suggesting they may also be beneficial for fatigue properties. To probe this hypothesis, in situ transmission electron microscopy fatigue cycling is performed on Cu-1 at.% Zr thin films thermally treated to have either only ordered grain boundaries or to contain amorphous intergranular films. The sample with only ordered grain boundaries experienced grain coarsening at crack initiation followed by unsteady crack propagation and extensive nanocracking, whereas the sample containing amorphous intergranular films had no grain coarsening at crack initiation followed by steady crack propagation and distributed plastic activity. Microstructural design for control of these behaviors through simple thermal treatments can allow for the improvement of nanocrystalline metal fatigue toughness.

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“…AIFs not only stabilize the grain size, but they can do so at elevated temperatures where these structures are the preferred state. For example, a new grain size stabilization regime was found at 1200 °C (approximately 70% of the melting temperature) in nanocrystalline Ni-W due to AIF formation [35]. This new region of stability appeared after traditional solute segregation had begun to fail.…”

Section: Introductionmentioning

confidence: 99%

Amorphous intergranular films mitigate radiation damage in nanocrystalline Cu-Zr

et al. 2020

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Nanocrystalline metals are promising radiation tolerant materials due to their large interfacial volume fraction, but irradiation-induced grain growth can eventually degrade any improvement in radiation tolerance. Therefore, methods to limit grain growth and simultaneously improve the radiation tolerance of nanocrystalline metals are needed. Amorphous intergranular films are unique grain boundary structures that are predicted to have improved sink efficiencies due to their increased thickness and amorphous structure, while also improving grain size stability.In this study, ball milled nanocrystalline Cu-Zr alloys are heat treated to either have only ordered grain boundaries or to contain amorphous intergranular films distributed within the grain boundary network, and are then subjected to in situ transmission electron microscopy irradiation and ex situ irradiation. Differences in defect density and grain growth due to grain boundary complexion type are then investigated. When amorphous intergranular films are incorporated within the material, fewer and smaller defect clusters are observed while grain growth is also limited, leading to nanocrystalline alloys with improved radiation tolerance.

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Amorphous complexions enable a new region of high temperature stability in nanocrystalline Ni-W

Cited by 52 publications

References 58 publications

Thick amorphous complexion formation and extreme thermal stability in ternary nanocrystalline Cu-Zr-Hf alloys

Thick amorphous complexion formation and extreme thermal stability in ternary nanocrystalline Cu-Zr-Hf alloys

In Situ High-Cycle Fatigue Reveals Importance of Grain Boundary Structure in Nanocrystalline Cu-Zr

Amorphous intergranular films mitigate radiation damage in nanocrystalline Cu-Zr

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