Materials selection rules for amorphous complexion formation in binary metallic alloys

Schuler, Jennifer D.; Rupert, Timothy J.

doi:10.1016/j.actamat.2017.08.042

Cited by 86 publications

(58 citation statements)

References 83 publications

(132 reference statements)

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“…Irradiation of amorphous SiOC/crystalline Fe multilayers, which mimic the amorphous/crystalline regions at the grain boundary when AIFs are present, showed intermixing at 50 K but then transitioned to demixing at 573 K, indicating improved radiation tolerance at elevated temperatures [101]. Cu-Zr is a miscible alloy, chosen in part specifically for this characteristic to promote AIF formation at the grain boundaries [55]. STEM-EDS was performed on the ordered grain boundary and AIF-containing samples after both the 25 °C and 200 °C ex situ irradiation.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

Amorphous intergranular films mitigate radiation damage in nanocrystalline Cu-Zr

et al. 2020

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“…First, there is evidence that all of the added dopants should segregate to defects. Zr [21][22][23] and Ag [40,41,54] have been observed to segregate to grain boundaries in Cu-based alloys, while the interfacial segregation of Cu [55][56][57] in Al-based alloys has also been reported.…”

Section: Methodsmentioning

confidence: 99%

“…Grain boundary segregation can also be used to stabilize nanoscale grain sizes, because segregated dopants reduce both grain boundary energy and mobility [14][15][16]. For example, stable nanostructures were found in alloy systems such as Cu-Zr [21][22][23], Cu-Hf [21], Ni-Zr [21], W-Ti [24], Cu-Bi [25], and Cu-Cr [26].…”

Section: Introductionmentioning

confidence: 99%

Atomistic modeling of interfacial segregation and structural transitions in ternary alloys

Rupert

2018

J Mater Sci

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Grain boundary engineering via dopant segregation can dramatically change the properties of a material. For metallic systems, most current studies concerning interfacial segregation and subsequent transitions of grain boundary structure are limited to binary alloys, yet many important alloy systems contain more than one type of dopant. In this work, hybrid Monte Carlo/molecular dynamics simulations are performed to investigate the behavior of dopants at interfaces in two model ternary alloy systems: Cu-Zr-Ag and Al-Zr-Cu. Trends in boundary segregation are studied, as well as the propensity for the grain boundary structure to become disordered at high temperature and doping concentration. For Al-Zr-Cu, we find that the two solutes prefer to occupy different sites at the grain boundary, leading to a synergistic doping effect. Alternatively, for Cu-Zr-Ag, there is site competition because the preferred segregation sites are the same. Finally, we find that thicker amorphous intergranular films can be formed in ternary systems by controlling the concentration ratio of different solute elements.

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“…To begin, we must select alloying elements and compositions which will allow for dopant segregation to the grain boundaries and possibly transformation into amorphous complexions. As mentioned previously, Schuler and Rupert developed materials selection guidelines for AIF formation which emphasized a positive enthalpy of segregation and a negative enthalpy of mixing [32]. Bulk metallic glass formation guidelines suggest that multicomponent systems with three or more elements, a negative heat of mixing, and an atomic size mismatch greater than 12% encourage the formation of amorphous phases [33].…”

Section: Methodsmentioning

confidence: 99%

“…Bulk metallic glass formation guidelines suggest that multicomponent systems with three or more elements, a negative heat of mixing, and an atomic size mismatch greater than 12% encourage the formation of amorphous phases [33]. The thermal stability and mechanical behavior of nanocrystalline Cu has been widely studied [7,36,37], and both Zr and Hf dopants have already been shown experimentally to exhibit strong tendencies to segregate to grain boundaries in Cu [29,32]. Zr and Hf both possess positive enthalpies of segregation and negative enthalpies of mixing with respect to Cu [15,38] and have atomic radii that are 25% and 24% larger than Cu, respectively.…”

Section: Methodsmentioning

confidence: 99%

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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Materials selection rules for amorphous complexion formation in binary metallic alloys

Cited by 86 publications

References 83 publications

Amorphous intergranular films mitigate radiation damage in nanocrystalline Cu-Zr

Amorphous intergranular films mitigate radiation damage in nanocrystalline Cu-Zr

Atomistic modeling of interfacial segregation and structural transitions in ternary alloys

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

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