Unveiling the mechanisms of motion of synchro-Shockley dislocations in Laves phases

Xie, Zhuocheng; Chauraud, Dimitri; Atila, Achraf; Bitzek, Erik; Korte‐Kerzel, Sandra; Guénolé, Julien

doi:10.1103/physrevmaterials.7.053605

Cited by 4 publications

(1 citation statement)

References 62 publications

(91 reference statements)

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“…Especially when studying fracture, care must be taken that the potential correctly reproduces the bonding situation around the highly-stressed crack tip [20]. Initial fracture tests with a modified embedded atom method (M-EAM) potential for the Ca-Al system [21], which was successfully used for simulations of plasticity in CaAl2 [22], showed artificial phase transformations at the crack tip. Therefore, we performed all fracture simulations on a model NbCr2 C15 Laves phase, for which an EAM potential was specifically fitted to replicate crack advance [23].…”

Section: Atomistic Simulationsmentioning

confidence: 99%

Microscale Fracture Toughness Investigation of the Caal2 C15 Laves Phase

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Rehman²,

Tian

et al. 2022

SSRN Journal

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Section: Atomistic Simulationsmentioning

confidence: 99%

Microscale Fracture Toughness Investigation of the Caal2 C15 Laves Phase

Best

Rehman²,

Tian

et al. 2022

SSRN Journal

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On the Temperature and Composition Dependence of Non‐basal Stacking Faults in C14 Laves Phases

Xie,

Chauraud,

Bitzek

et al. 2024

Adv Eng Mater

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Activation of non‐basal slip is essential in improving the deformability of hexagonal crystals. However, for complex intermetallics such as Laves phase, the mechanism of non‐basal slip remains largely unknown. In this work, the prismatic slip systems of C14 Laves phase crystals and possible metastable states along the slip paths are assessed using atomistic simulations. Multiple prismatic stacking fault states with the same projected positions of atoms but different site occupancies and chemical distributions are identified at different inter‐atomic layers, temperatures and chemical compositions. The formation of energetically favorable prismatic stacking faults involves short‐range diffusion which implies the thermally activated nature of prismatic slip. The outcomes of this work advance the understanding of temperature and composition‐dependent non‐basal slip in Laves phases.

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Fracture of the C15 CaAl2 Laves phase at small length scales

Best,

Kanjilal,

Ghafarollahi

et al. 2024

J Mater Sci

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The cubic C15 CaAl2 Laves phase is an important brittle intermetallic precipitate in ternary Mg–Al–Ca structural alloys. Although knowledge of the mechanical properties of the co-existing phases is essential for the design of improved alloys, the fracture toughness of the C15 CaAl2 intermetallic has not yet been studied experimentally due to limitations posed by macroscale testing of defect-free specimens. Here, miniaturised testing techniques like micropillar splitting and microcantilever bending methods are used to experimentally determine the fracture toughness of the CaAl2 Laves phase. It is found that the toughness value of ~ 1 MPa·√m obtained from pillar splitting with a sharp cube corner geometry is largely insensitive to sample heat treatment, the ion beam used during fabrication, micropillar diameter, and surface orientation. From correlative nanoindentation and electron channelling contrast imaging supported by electron backscatter diffraction, fracture is observed to take place mostly on {011} planes. Atomistic fracture simulations on a model C15 NbCr2 Laves phase showed that the preference of {011} cleavage planes over the more energetically favourable {111} planes is due to lattice trapping and kinetics controlling fracture planes in complex crystal structures, which may provide insights into the experimental results for CaAl2. Using rectangular microcantilever bending tests where the notch plane was misoriented to the closest possible {112} cleavage plane by ~ 8° and the closest {001}, {011}, and {111} planes by > 20°, a toughness of ~ 2 MPa·√m was determined along with the electron microscopy observation of significant deviations of the crack path, demonstrating that preferential crystallographic cleavage planes determine the toughness in this material. Further investigation using pentagonal microcantilevers with precise alignment of the notch with the cleavage planes revealed similar fracture toughness values for different low-index planes. The results presented here are the first detailed experimental study of fracture toughness of the C15 CaAl2 Laves phase and can be understood in terms of crack plane and crack front-dependent fracture toughness. Graphical Abstract

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Unveiling the mechanisms of motion of synchro-Shockley dislocations in Laves phases

Cited by 4 publications

References 62 publications

Microscale Fracture Toughness Investigation of the Caal2 C15 Laves Phase

Microscale Fracture Toughness Investigation of the Caal2 C15 Laves Phase

On the Temperature and Composition Dependence of Non‐basal Stacking Faults in C14 Laves Phases

Fracture of the C15 CaAl2 Laves phase at small length scales

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