New nanoscale toughening mechanisms mitigate embrittlement in binary nanocrystalline alloys

Heckman, Nathan M.; Foiles, Stephen M.; O’Brien, C. J.; Chandross, Michael; Barr, Christopher M.; Argibay, Nicolas; Hattar, Khalid Mikhiel; Lu, Ping; Adams, David P.; Boyce, Brad Lee

doi:10.1039/c8nr06419a

Cited by 29 publications

(13 citation statements)

References 66 publications

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“…NC Al 94.5 Fe 5.5 was chosen to investigate the orientationdependent properties. Few voids at GBs were identified in Al 94.5 Fe 5.5 in the underfocus TEM imaging condition (Note that voids were readily identified in texture-less Al-TM alloys with coarse columnar structure) and the elemental selection is relatively exempted from the GB embrittlement according to Gibson and Schuh model [121,122]. Figure 6a shows that Al 94.5 Fe 5.5 has an ITB spacing of 22 nm and a grain size of 5 nm.…”

Section: In Situ Micromechanical Tension and Compressionmentioning

confidence: 99%

Achieving strong and stable nanocrystalline Al alloys through compositional design

Wang

et al. 2021

Journal of Materials Research

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Al alloys often suffer from low mechanical strength and lack high-temperature microstructural and mechanical robustness. A series of binary and ternary nanocrystalline (NC) Al transition metal alloys with supersaturated solid solution and columnar nanograins have been recently developed by using magnetron sputtering, manifesting a new realm of mechanical properties and thermal stability. Distinct solutes cause evident differences in the phase transformations and efficiencies for grain refinement and crystalline-to-amorphous transition. Certain sputtered Al-TM alloys have shown room-temperature mechanical strengths greater than 2 GPa and outstanding thermal stability up to 400 °C. In addition, the NC Al alloys show mechanical anisotropy and tension–compression asymmetry, revealed by micromechanical tests. Through the process encapsulating various compositionally distinct systems, we attempt to illuminate the solute effects on grain refinement and properties and more importantly, tentatively unravel the design criteria for high-strength and yet thermally stable NC Al alloys. Graphic Abstract

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Section: In Situ Micromechanical Tension and Compressionmentioning

confidence: 99%

Achieving strong and stable nanocrystalline Al alloys through compositional design

Wang

et al. 2021

Journal of Materials Research

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“…51,52 Such GB embrittlement has been observed experimentally; however, modest solute content may lead to inhomogeneous embrittlement and subsequent distributed stable nanocracks rather than a single catastrophic crack. 53 Such distributed cracking is a known toughening mechanism.…”

Section: Fatigue and Fracture Of Nanocrystalline Metals And Alloysmentioning

confidence: 99%

Fatigue and fracture of nanostructured metals and alloys

et al. 2021

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Metals and alloys with nanoscale structural features (such as grain size or twin thickness <100 nm) exhibit exceptional strength and unusual deformation mechanisms. But, the suppressed dislocation slip, grain-boundary instability, and limited strain hardening in these nanostructured metals can be detrimental to fatigue and fracture properties. In this article, recent advances in understanding the structural origins of fatigue and fracture resistance of nanocrystalline and nanotwinned metals and alloys are reviewed. Based on this understanding, microstructural engineering strategies, such as gradient grain size, controlled boundary mobility, or hierarchical nanotwins, alter the deformation modes and provide promising paths to develop nanostructured materials with improved fatigue and fracture properties.

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“…Thus, reducing the thermodynamic drive for grain growth should oppose the deleterious effects of applied stresses in tribological applications. One recent study focused on Pt-Au, as it is the only proposed binary alloy made of noble metals, eliminating the possibility of precipitate strengthening by mechanical mixing with incorporated oxide particles [71,238,[247][248][249]. This alloy has the added benefit of being immediately applicable in electrical contact applications.…”

Section: Routes For Promoting Grain Boundary Sliding In Metalsmentioning

confidence: 99%

Friction of Metals: A Review of Microstructural Evolution and Nanoscale Phenomena in Shearing Contacts

Chandross

Argibay

2021

Tribol Lett

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The friction behavior of metals is directly linked to the mechanisms that accommodate deformation. We examine the links between mechanisms of strengthening, deformation, and the wide range of friction behaviors that are exhibited by shearing metal interfaces. Specifically, the focus is on understanding the shear strength of nanocrystalline and nanostructured metals, and conditions that lead to low friction coefficients. Grain boundary sliding and the breakdown of Hall–Petch strengthening at the shearing interface are found to generally and predictably explain the low friction of these materials. While the following is meant to serve as a general discussion of the strength of metals in the context of tribological applications, one important conclusion is that tribological research methods also provide opportunities for probing the fundamental properties and deformation mechanisms of metals.

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New nanoscale toughening mechanisms mitigate embrittlement in binary nanocrystalline alloys

Abstract: Inhomogeneous chemical segregation to grain boundaries in nanocrystalline metals can lead to a new toughening mechanism called compositional crack arrest.

Cited by 29 publications

References 66 publications

Achieving strong and stable nanocrystalline Al alloys through compositional design

Achieving strong and stable nanocrystalline Al alloys through compositional design

Fatigue and fracture of nanostructured metals and alloys

Friction of Metals: A Review of Microstructural Evolution and Nanoscale Phenomena in Shearing Contacts

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