Plastic deformation of the CaMg2 C14-Laves phase from 50 - 250°C

Freund, M.; Andre, D.; Zehnder, Christoffer; Rempel, Hanno; Gerber, Dennis; Zubair, Muhammad; Sandlöbes-Haut, Stefanie; Gibson, J. S.; Korte‐Kerzel, Sandra

doi:10.1016/j.mtla.2021.101237

Cited by 22 publications

(19 citation statements)

References 66 publications

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“…The small activation volume of kink-pair nucleation and short-range shuffling of dislocation motion (a few b 3 ) in the simulated C14 CaMg 2 correlates well with the experimental estimations on C14 CaMg 2 (Ω = 13b 3 , based on the experimental data obtained from micropillar compression tests [37,38] and the calculation details are described in the Supplementary information) and other Laves phases [39][40][41][42]. Two 30°synchro-Shockley dislocations with edge components of Burgers vectors in opposite directions and different core structures were identified as shown in FIG.…”

Section: Stress-dependent Activation Energy and Volumesupporting

confidence: 82%

“…we find an activation volume of Ω = 13b 3 . This volume is higher than expected for a purely lattice resistance controlled mechanism, however, given the large uncertainty from the underlying experimental data and a possible underestimation of the critical resolved shear stress versus temperature slope due to a lower strain rate used at the lowest temperature [37,38], the calculations in this study and experiments appear consistent at least.…”

Section: Supplementary Informationsupporting

confidence: 54%

“…Unveiling the mechanisms of motion of synchro-Shockley dislocations The available data on specifically basal slip in the C14 CaMg 2 Laves phase studied here allows at least an approximate comparison of the activation volumes [37]. Using the scarce, slip system-specific data with a linear fit through the data points of the critical resolved shear stress from single crystal micropillar compression at room temperature, 150 and 250 °C [37] (giving a change in stress of 0.09 GPa) and assuming motion of 1/3 [10 10] with |b| = 0.365 nm, a dislocation density ρ m of 10 12 m −2 , an attempt frequency ν A of 10 11 s −1 , and an average shear strain rate γ of 0.001 s −1 in…”

Section: Supplementary Informationmentioning

confidence: 99%

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

Xie,

Chauraud,

Atila

et al. 2022

Preprint

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In Laves phases, synchroshear is the dominant basal slip mechanism. It is accomplished by the glide of synchro-Shockley dislocations. However, the atomic-scale mechanisms of motion of such zonal dislocations are still not well understood. In this work, using atomistic simulations, two 30°synchro-Shockley dislocations with different Burgers vectors and core structures and energies are identified. We demonstrate that nucleation and propagation of kink pairs is the energetically favorable mechanism for the motion of the synchro-Shockley dislocation (partial I). Vacancy hopping and interstitial shuffling are identified as two key mechanisms related to kink propagation and we investigated how vacancies and antisite defects assist kink nucleation and propagation, which is crucial for kink mobility. Additionally, we identified a mechanism of non-sequential atomic shuffling for the motion of the synchro-Shockley dislocation (partial II). These findings provide insights into the dependency on temperature and chemical composition of plastic deformation induced by zonal dislocations in Laves phases and the many related topologically close-packed phases.

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Section: Stress-dependent Activation Energy and Volumesupporting

confidence: 82%

Section: Supplementary Informationsupporting

confidence: 54%

Section: Supplementary Informationmentioning

confidence: 99%

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

Xie,

Chauraud,

Atila

et al. 2022

Preprint

Self Cite

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“…On the other hand, the Nb35 alloy contains only a small fraction (7.4 wt.%) of FCC solid solution embedded into the HCP Laves phase. Therefore, the influence of the FCC solid solution grains is limited and the behavior of the Nb35 alloy at 800 °C is dominated by the deformation of the hexagonal Laves phase through the activation of more slip systems at higher stresses [ 27 ]. In consequence, the material shows much higher values of CYS and UCS, 1695 and 1817 MPa, respectively.…”

Section: Resultsmentioning

confidence: 99%

Microstructure and Mechanical Properties of Spark Plasma Sintered CoCrFeNiNbX High-Entropy Alloys with Si Addition

et al. 2023

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Three mechanically alloyed (MA) and spark plasma sintered (SPS) CoCrFeNiNbX (X = 5, 20, and 35 at.%) alloys with an addition of 5 at.% of SiC were investigated. The face-centered cubic (FCC) high-entropy solid solution, NbC carbides, and hexagonal Laves phase already developed during MA. In addition, the SPS compacting led to the formation of oxide particles in all alloys, and the Cr7C3 carbides in the Nb5 alloy. The fraction of the FCC solid solution decreased with increasing Nb concentration at the expense of the NbC carbide and the Laves phase. Long-term annealing at 800 °C led to the disappearance of the Cr7C3 carbide in the Nb5 alloy, and new oxides—Ni6Nb6O, Cr2O3, and CrNbO4—were formed. At laboratory temperature, the Nb5 alloy, containing only the FCC matrix and carbide particles, was relatively strong and very ductile. At a higher Nb content (Nb20 and Nb35), the alloys became brittle. After annealing for 100 h at 800 °C, the Nb5 alloy conserved its plasticity and the Nb20 and Nb35 alloys maintained or even increased their brittleness. When tested at 800 °C, the Nb5 and Nb20 alloys deformed almost identically (CYS ~450 MPa, UTS ~500 MPa, plasticity ~18%), whereas the Nb35 alloy was much stronger (CYS of 1695 MPa, UCS of 1817 MPa) and preserved comparable plasticity.

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“…In contrast to the modeled stoichiometry range, ranging, for example, from 1.99 to 2.02 at 290 °C (see Figure 3 d), the experimentally obtained composition range, in which phase-pure Mg 2 Ca was obtained through XRD, was reported to be between 1.7 to 2.2, based on the sublimation-dominated sputtering process of Mg-Ca thin films [ 12 ]. In general, controversial results regarding the stoichiometry range of Mg 2 Ca are reported in the literature, ranging from a line compound [ 29 ] to an off-stoichiometric formation [ 12 , 30 , 31 ]. To investigate the stoichiometry range of intermetallic Mg 2 Ca, compositionally graded Mg-Ca thin films were synthesized without intentional substrate heating and were subsequently annealed in vacuum without atmosphere exposure at varying temperatures.…”

Section: Resultsmentioning

confidence: 99%

CALPHAD-Based Modelling of the Temperature–Composition–Structure Relationship during Physical Vapor Deposition of Mg-Ca Thin Films

et al. 2023

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The temperature-dependent composition and phase formation during the physical vapor deposition (PVD) of Mg-Ca thin films is modeled using a CALPHAD-based approach. Considering the Mg and Ca sublimation fluxes calculated based on the vapor pressure obtained by employing thermochemical equilibrium calculations, the experimentally observed synthesis-temperature trends in the thin-film composition and phase formation were reproduced. The model is a significant step towards understanding how synthesis parameters control composition and, therefore, phase formation in the PVD of metals with high vapor pressures.

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Plastic deformation of the CaMg2 C14-Laves phase from 50 - 250°C

Cited by 22 publications

References 66 publications

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

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

Microstructure and Mechanical Properties of Spark Plasma Sintered CoCrFeNiNbX High-Entropy Alloys with Si Addition

CALPHAD-Based Modelling of the Temperature–Composition–Structure Relationship during Physical Vapor Deposition of Mg-Ca Thin Films

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