Dislocation motion and multiplication at the deformation of MgO single crystals in the high voltage electron microscope

Appel, F.; Bethge, H.; Messerschmidt, U.

doi:10.1002/pssa.2210420104

Cited by 49 publications

(16 citation statements)

References 12 publications

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“…4(b)). Nevertheless, two screw dislocation arms tagging behind an edge dipole trail are easily annihilated, as evidenced in single crystal MgO during in situ tensile test 27 …”

Section: Discussionmentioning

confidence: 99%

Deformation Microstructure in (001) Single Crystal Strontium Titanate by Vickers Indentation

Yang

2009

Journal of the American Ceramic Society

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Recent interests on the plastic deformation of strontium titanate (SrTiO3) are derived from its unusual ductile‐to‐brittle‐to‐ductile transition (DBDT). The transition is divided into three regimes (A, B, and C) corresponding to the temperature range of 113–1053 K (−160° to 780°C), 1053 to ∼1503 K (780° to ∼1230°C), and ∼1503–1873 K (∼1230° to 1600°C), discovered by Sigle and colleagues in the MPI‐Stuttgart. We report the dislocation substructures in (001) single crystal SrTiO3 deformed by Vickers indentation at room temperature, studied by scanning and transmission electron microscopy. Dislocation dipoles of screw and edge character are observed and confirmed by inside–outside contrast using ±g‐vector by weak‐beam dark field imaging. They are formed by edge trapping, jog dragging, and cross slip pinching‐off. Similar to dipole breaking off in deformed sapphire (α‐Al2O3) at 1200°C and γ‐TiAl intermetallic at room temperature, the dipoles pinch off at one end, and emit a string of loops at trail. Two sets of slip systems {110}〈〉 and {100}〈011〉 are activated under both 100 g and 1 kg load. The suggestion is that plastic deformation has reached the stage II work hardening, which is characterized by multiplication of dislocations through cross slip, interactions between dislocations, and operating of multiple slip systems.

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“…4(b)). Nevertheless, two screw dislocation arms tagging behind an edge dipole trail are easily annihilated, as evidenced in single crystal MgO during in situ tensile test 27 …”

Section: Discussionmentioning

confidence: 99%

Deformation Microstructure in (001) Single Crystal Strontium Titanate by Vickers Indentation

Yang

2009

Journal of the American Ceramic Society

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“…1/2h1 1 0i{1 1 0} dislocation glide involves the nucleation of kink-pairs, typical of the lattice friction regime. This specific process leads to a characteristic dislocation microstructure made of rate-controlling long screw dislocations [32,33] which are also observed in body-centered cubic (bcc) metals at low temperature [34,35]. Above a transition temperature ($600 K for 1/2h1 1 0i{1 1 0} slip systems and 1500 K for 1/2h1 1 0i{1 0 0}), lattice friction is overcome and plastic strain is accommodated by curved dislocations [36,37], ruled by the strength of dislocationdislocation "forest" interactions [38,39].…”

Section: Introductionmentioning

confidence: 99%

In situ investigation of MgO nanocube deformation at room temperature

et al. 2015

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The mechanical behavior of h1 0 0i-oriented MgO nanocubes is investigated using in situ transmission electron microscopy (TEM) compression tests at room temperature and molecular dynamics simulations. Experiments show high strength and ductility, in addition to specific deformation mechanisms interpreted by the simulation. The nucleation and the propagation of 1/2h1 1 0i{1 1 0} dislocations are at the onset of the plastic deformation. The different deformation processes as well as the possible formation of a dislocation network during compression are discussed.

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“…For 1 ⁄2<110>{110}, T a ranges from 600 K to 800 K depending on the experimental dataset. CRSS vary less rapidly for 1 ⁄2<110>{100} slip systems and T a > 1300 K. Dislocation microstructures developed during single crystal compression tests were characterized using in situ TEM [24,25]. At room temperature, straight and long screw dislocations are observed in both the {110} and the {100} slip planes [24,26].…”

Section: Temperature-dependent Dislocation Microstructuresmentioning

confidence: 99%

“…In the early 1970s, the group of Messerschmidt (Halle, Germany) did an impressive work quantifying the interaction between dislocations and point defects, especially to interpret observations made in the High-Voltage Electron Microscope (HVEM) [12,24,[35][36][37][38][39][40][41][42]. Among others, a model for point obstacle crossing activation energy is proposed [37] as well as a comparison between TEM observations and calculation of point defect distance distribution [43].…”

Section: On the Role Of Impurities And Heat Treatments On Crss And DImentioning

confidence: 99%

“…CRSS vary less rapidly for 1 ⁄2<110>{100} slip systems and T a > 1300 K. Dislocation microstructures developed during single crystal compression tests were characterized using in situ TEM [24,25]. At room temperature, straight and long screw dislocations are observed in both the {110} and the {100} slip planes [24,26]. Their velocity is assumed to follow a stress-exponent [16,27] or an Arrhenius-like dependency [28,29].…”

Section: Temperature-dependent Dislocation Microstructuresmentioning

confidence: 99%

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Dislocations and Plastic Deformation in MgO Crystals: A Review

et al. 2018

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This review paper focuses on dislocations and plastic deformation in magnesium oxide crystals. MgO is an archetype ionic ceramic with refractory properties which is of interest in several fields of applications such as ceramic materials fabrication, nano-scale engineering and Earth sciences. In its bulk single crystal shape, MgO can deform up to few percent plastic strain due to dislocation plasticity processes that strongly depend on external parameters such as pressure, temperature, strain rate, or crystal size. This review describes how a combined approach of macro-mechanical tests, multi-scale modeling, nano-mechanical tests, and high pressure experiments and simulations have progressively helped to improve our understanding of MgO mechanical behavior and elementary dislocation-based processes under stress.

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Dislocation motion and multiplication at the deformation of MgO single crystals in the high voltage electron microscope

Cited by 49 publications

References 12 publications

Deformation Microstructure in (001) Single Crystal Strontium Titanate by Vickers Indentation

Deformation Microstructure in (001) Single Crystal Strontium Titanate by Vickers Indentation

In situ investigation of MgO nanocube deformation at room temperature

Dislocations and Plastic Deformation in MgO Crystals: A Review

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