On the structure of defects in the Fe7Mo6 μ-Phase

Schröders, Sebastian; Sandlöbes, Stefanie; Berkels, Benjamin; Korte‐Kerzel, Sandra

doi:10.1016/j.actamat.2019.01.045

Cited by 44 publications

(41 citation statements)

References 54 publications

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“…The synchroshear mechanism is the most favorable mechanism for basal slip in the C14 Laves phase. It has been confirmed by our previous study using nudged-elastic band (NEB) calculations [28] and experimentally in the Laves phase layer of the µ-phase crystal structure [43,44]. It is likely to occur in the same way on the basal plane of the C36 phase and the {111} plane of the C15 phase.…”

Section: Identification Of Basal Slip In the Hexagonal C14 Structure: The Synchroshear Mechanismsupporting

confidence: 63%

Laves phase crystal analysis (LaCA): Atomistic identification of lattice defects in C14 and C15 topologically close-packed phases

Xie

Chauraud

Bitzek

et al. 2021

Journal of Materials Research

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The identification of defects in crystal structures is crucial for the analysis of atomistic simulations. Many methods to characterize defects that are based on the classification of local atomic arrangement are available for simple crystalline structures. However, there is currently no method to identify both, the crystal structures and internal defects of topologically close-packed (TCP) phases such as Laves phases. We propose a new method, Laves phase crystal analysis (LaCA), to characterize the atomic arrangement in Laves crystals by interweaving existing structural analysis algorithms. The new method can identify the polytypes C14 and C15 of Laves phases, typical crystallographic defects in these phases, and common deformation mechanisms such as synchroshear and non-basal dislocations. Defects in the C36 Laves phase are detectable through deviations from the periodic arrangement of the C14 and C15 structures that make up this phase. LaCA is robust and extendable to other TCP phases. Graphic abstract

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Section: Identification Of Basal Slip In the Hexagonal C14 Structure: The Synchroshear Mechanismsupporting

confidence: 63%

Laves phase crystal analysis (LaCA): Atomistic identification of lattice defects in C14 and C15 topologically close-packed phases

Xie

Chauraud

Bitzek

et al. 2021

Journal of Materials Research

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“…It is important to note, however, that for complex intermetallics, a deformation mechanism beyond simple dislocation glide may be operating, for example, the synchroshear mechanisms on the basal plane of the µ-phase [ 15 ] or formation of meta-dislocations [ 45 ]. In these cases, a simple identification of the slip plane and Burgers vector are not enough to infer the atomic mechanisms of dislocation glide.…”

Section: Methodsmentioning

confidence: 99%

“…In these cases, a simple identification of the slip plane and Burgers vector are not enough to infer the atomic mechanisms of dislocation glide. Here, HR-TEM may be of help [ 15 , 45 ], but will require careful alignment and further thinning of the sample for the atomic-scale visualisation of defect structures.…”

Section: Methodsmentioning

confidence: 99%

“…Here, we will focus on single crystalline BCC [ 8 ] and intermetallic crystals [ 15 , 16 ] as examples, but the methods, analyses and code can be applied to any material that forms sufficiently clear traces of plasticity on its surface and in which these traces are governed by the crystal structure.…”

Section: Introductionmentioning

confidence: 99%

“…With respect to the intermetallics taken as an example here [ 15 , 16 ], there are not only a great number that remain to be studied, but many different applications in which their mechanical properties need to be known beyond a simple stiffness or hardness. They are used as phases for alloy reinforcement [ 1 ], they form unintentionally in modern materials with high alloying contents, such as the superalloys [ 17 , 18 ], and for the optimistic researcher they may still be hiding a new class of bulk alloys amongst their numbers that combines safety as a structural material with great resistance to harsh environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

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Finding and Characterising Active Slip Systems: A Short Review and Tutorial with Automation Tools

et al. 2021

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The behaviour of many materials is strongly influenced by the mechanical properties of hard phases, present either from deliberate introduction for reinforcement or as deleterious precipitates. While it is, therefore, self-evident that these phases should be studied, the ability to do so—particularly their plasticity—is hindered by their small sizes and lack of bulk ductility at room temperature. Many researchers have, therefore, turned to small-scale testing in order to suppress brittle fracture and study the deformation mechanisms of complex crystal structures. To characterise the plasticity of a hard and potentially anisotropic crystal, several steps and different nanomechanical testing techniques are involved, in particular nanoindentation and microcompression. The mechanical data can only be interpreted based on imaging and orientation measurements by electron microscopy. Here, we provide a tutorial to guide the collection, analysis, and interpretation of data on plasticity in hard crystals. We provide code collated in our group to help new researchers to analyse their data efficiently from the start. As part of the tutorial, we show how the slip systems and deformation mechanisms in intermetallics such as the Fe7Mo6 μ-phase are discovered, where the large and complex crystal structure precludes determining a priori even the slip planes in these phases. By comparison with other works in the literature, we also aim to identify “best practises” for researchers throughout to aid in the application of the methods to other materials systems.

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Tailoring the Plasticity of Topologically Close‐Packed Phases via the Crystals’ Fundamental Building Blocks

et al. 2023

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Brittle topologically close‐packed precipitates form in many advanced alloys. Due to their complex structures, little is known about their plasticity. Here, a strategy is presented to understand and tailor the deformability of these complex phases by considering the Nb–Co µ‐phase as an archetypal material. The plasticity of the Nb–Co µ‐phase is controlled by the Laves phase building block that forms parts of its unit cell. It is found that between the bulk C15–NbCo2 Laves and Nb–Co µ‐phases, the interplanar spacing and local stiffness of the Laves phase building block change, leading to a strong reduction in hardness and stiffness, as well as a transition from synchroshear to crystallographic slip. Furthermore, as the composition changes from Nb6Co7 to Nb7Co6, the Co atoms in the triple layer are substituted such that the triple layer of the Laves phase building block becomes a slab of pure Nb, resulting in inhomogeneous changes in elasticity and a transition from crystallographic slip to a glide‐and‐shuffle mechanism. These findings open opportunities to purposefully tailor the plasticity of these topologically close‐packed phases in the bulk by manipulating the interplanar spacing and local shear modulus of the fundamental crystal building blocks at the atomic scale.

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On the structure of defects in the Fe7Mo6 μ-Phase

Cited by 44 publications

References 54 publications

Laves phase crystal analysis (LaCA): Atomistic identification of lattice defects in C14 and C15 topologically close-packed phases

Laves phase crystal analysis (LaCA): Atomistic identification of lattice defects in C14 and C15 topologically close-packed phases

Finding and Characterising Active Slip Systems: A Short Review and Tutorial with Automation Tools

Tailoring the Plasticity of Topologically Close‐Packed Phases via the Crystals’ Fundamental Building Blocks

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