The Zinc Story under High Pressure

Takemura, Kenichi

doi:10.4236/jmmce.2019.75024

Cited by 3 publications

(1 citation statement)

References 61 publications

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“…Most hcp ‐metals, including hcp ‐iron, are though less anisotropic than zinc (e.g., Takemura, 2019; Tromans, 2011) and it is not known how ubiquitous internal stress superplasticity is in hcp ‐metals. But at the homologous temperatures of the inner‐core (T/T m ≲ 1) dynamic recrystallization will be extremely rapid.…”

Section: Discussionmentioning

confidence: 99%

Experimental Observation of a New Attenuation Mechanism in hcp‐Metals That May Operate in the Earth's Inner Core

Hunt,

Walker,

Lord

et al. 2024

Geochem Geophys Geosyst

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Seismic observations show the Earth's inner core has significant and unexplained variation in seismic attenuation with position, depth and direction. Interpreting these observations is difficult without knowledge of the visco‐ or anelastic dissipation processes active in iron under inner core conditions. Here, a previously unconsidered attenuation mechanism is observed in zinc, a low pressure analog of hcp‐iron, during small strain sinusoidal deformation experiments. The experiments were performed in a deformation‐DIA combined with X‐radiography, at seismic frequencies (∼0.003–0.1 Hz), high pressure and temperatures up to ∼80% of melting temperature. Significant dissipation (0.077 ≤ Q−1(ω) ≤ 0.488) is observed along with frequency dependent softening of zinc's Young's modulus and an extremely small activation energy for creep (⩽7 kJ mol−1). In addition, during sinusoidal deformation the original microstructure is replaced by one with a reduced dislocation density and small, uniform, grain size. This combination of behavior collectively reflects a mode of deformation called “internal stress superplasticity”; this deformation mechanism is unique to anisotropic materials and activated by cyclic loading generating large internal stresses. Here we observe a new form of internal stress superplasticity, which we name as “elastic strain mismatch superplasticity.” In it the large stresses are caused by the compressional anisotropy. If this mechanism is also active in hcp‐iron and the Earth's inner‐core it will be a contributor to inner‐core observed seismic attenuation and constrain the maximum inner‐core grain‐size to ≲10 km.

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Section: Discussionmentioning

confidence: 99%

Experimental Observation of a New Attenuation Mechanism in hcp‐Metals That May Operate in the Earth's Inner Core

Hunt,

Walker,

Lord

et al. 2024

Geochem Geophys Geosyst

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Electronic topological transitions in cadmium under pressure studied via theoretical and experimental x-ray absorption spectroscopy

Hinton,

Schacher,

Lee

et al. 2024

Phys. Rev. B

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Androgynous {101¯2} twin in zinc

Merkel,

Hilairet,

Wang

et al. 2024

Phys. Rev. Materials

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Under ambient conditions, Zn is a hexagonal metal with a large c/a ratio of 1.856. Plastic deformation is predominantly accommodated by basal 〈a〉 slip and compression twins on the {101¯2} planes. Increasing hydrostatic pressure drastically reduces the c/a ratio of Zn and, when a critical threshold of c/a=3 at about 10 GPa is crossed, the {101¯2} twins are predicted to change from compressive to tensile in nature. What happens at the transition point, when c/a=3, remains unknown. Here, we strain-cycle a textured polycrystalline sample of pure Zn at uniform hydrostatic pressures ranging between 2 and 17 GPa, over which the c/a ratio crosses the c/a=3 compressive-tensile transition for {101¯2} twins. During deformation, the state of the sample is monitored through x-ray diffraction to extract texture and internal strain evolution. By comparing the experimental results with the predictions of an elastoviscoplastic polycrystal simulation, we confirm the androgynous nature of {101¯2} twin response at low and high pressures. When c/a=3, polycrystalline Zn does not display any evidence of twinning and its plastic behavior is controlled by mostly basal and pyramidal 〈c+a〉 slip activity, with a very small contribution of prismatic 〈a〉 slip. Evidence for the activity of other {101¯n} twinning modes, which have been suggested for Zn under high pressure, are not observed. Published by the American Physical Society 2024

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The Zinc Story under High Pressure

Cited by 3 publications

References 61 publications

Experimental Observation of a New Attenuation Mechanism in hcp‐Metals That May Operate in the Earth's Inner Core

Experimental Observation of a New Attenuation Mechanism in hcp‐Metals That May Operate in the Earth's Inner Core

Electronic topological transitions in cadmium under pressure studied via theoretical and experimental x-ray absorption spectroscopy

Androgynous {101¯2} twin in zinc

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