Diffusionless Transformations

Delaey, L.

doi:10.1002/9783527603978.mst0392

Cited by 14 publications

(18 citation statements)

References 52 publications

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“…Their kinetic pathways follow either a diffusive nucleation or a diffusionless martensitic transformation with particles moving in concert 1 2 . Martensitic transformations occur widely in alloys 1 , ceramics, minerals, inorganic compounds 3 and proteins 4 . If the symmetries of the parent and the product lattices have a group–subgroup relation, then the parent lattice deforms continuously into the product lattice without any bond breaking 2 .…”

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confidence: 99%

Diffusive and martensitic nucleation kinetics in solid-solid transitions of colloidal crystals

Peng

Wang

et al. 2017

Nat Commun

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Solid–solid transitions between crystals follow diffusive nucleation, or various diffusionless transitions, but these kinetics are difficult to predict and observe. Here we observed the rich kinetics of transitions from square lattices to triangular lattices in tunable colloidal thin films with single-particle dynamics by video microscopy. Applying a small pressure gradient in defect-free regions or near dislocations markedly transform the diffusive nucleation with an intermediate-stage liquid into a martensitic generation and oscillation of dislocation pairs followed by a diffusive nucleus growth. This transformation is neither purely diffusive nor purely martensitic as conventionally assumed but a combination thereof, and thus presents new challenges to both theory and the empirical criterion of martensitic transformations. We studied how pressure, density, grain boundary, triple junction and interface coherency affect the nucleus growth, shape and kinetic pathways. These novel microscopic kinetics cast new light on control solid–solid transitions and microstructural evolutions in polycrystals.

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confidence: 99%

Diffusive and martensitic nucleation kinetics in solid-solid transitions of colloidal crystals

Peng

Wang

et al. 2017

Nat Commun

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“…The results of X-ray phase analysis (Fig. 1 ) reveal that the high-temperature β 1 phase (with ordered fcc structure of DO 3 type and a composition close to Cu 3 Al) is formed under cooling by quenching in water as a result of ordering of the high-temperature β phase with a bcc lattice of A2 type [ 17 ]. The subsequent annealing (for aging) of the high-temperature β 1 phase results in the precipitation of ferromagnetic ordered β 3 phase (with L2 1 -type structure and a composition close to Cu 2 AlMn) in the paramagnetic β 1 matrix [ 18 , 19 ], as evidenced by an appearance of weak intensity reflections from β 3 phase at appropriate diffraction angles.…”

Section: Resultsmentioning

confidence: 99%

Effect of Thermomagnetic Treatment on Structure and Properties of Cu–Al–Mn Alloy

et al. 2017

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The paper studies the influence of magnetic field on magnetic and mechanical properties of Cu–Mn–Al alloy under annealing. The comparative analysis of the magnetic field orientation impact on solid solution decomposition processes in a fixed annealing procedure is held using the methods of low-field magnetic susceptibility, specific magnetization, and microhardness test. The paper highlights changes in the magnetic and mechanical properties of Cu–Al–Mn alloy as the result of change in a critical size of forming precipitated ferromagnetic phase and determines correlation in the behavior of magnetic and mechanical properties of the alloy, depending on a critical nucleus size of forming precipitated ferromagnetic phase.

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“…High‐angle boundaries misoriented 65° about <110> occur within blade (Figs.␣5 and 6), wedge (Figs.␣4, 7, and 9), and massive domain (Figs.␣9 and 10) reidite variants. The 65° <110> boundaries likely represent transformation twins where the systematic misorientation is inherited from the parent zircon during phase transformation or mechanical twins that developed in order to minimize strain energy between reidite and the host zircon (Delaey 2006). Two prominent reidite twin domains misoriented 65° about <110> with different habits are discernible within the two grains that preserve the greatest amount of reidite (Figs.␣9 and 10).…”

Section: Discussionmentioning

confidence: 99%

Exceptional preservation of reidite in the Rochechouart impact structure, France: New insights into shock deformation and phase transition of zircon

Plan

Kenny

Erickson

et al. 2021

Meteorit & Planetary Scien

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Reidite, the high‐pressure zircon (ZrSiO4) polymorph, is a diagnostic indicator of impact events. Natural records of reidite are, however, scarce, occurring mainly as micrometer‐sized lamellae, granules, and dendrites. Here, we present a unique sequence of shocked zircon grains found within a clast from the Chassenon suevitic breccia (shock stage III) from the ˜200 Ma, 20–50 km wide Rochechouart impact structure in France. Our study comprises detailed characterization with scanning electron microscopy coupled with electron backscatter diffraction with the goal of investigating the stability and response of ZrSiO4 under extreme P–T conditions. The shocked zircon grains have preserved various amounts of reidite ranging from 4% up to complete conversion. The grains contain various variants of reidite, including the common habits: lamellae and granular reidite. In addition, three novel variants have been identified: blade, wedge, and massive domains. Several of these crosscut and offset each other, revealing that reidite can form at multiple stages during an impact event. Our data provide evidence that reidite can be preserved in impactites to a much greater extent than previously documented. We have further characterized reversion products of reidite in the form of fully recrystallized granular zircon grains and minute domains of granular zircon in reidite‐bearing grains that occur in close relationship to reidite. Neoblasts in these grains have a distinct crystallography that is the result of systematic inheritance of reidite. We interpret that the fully granular grains have formed from prolonged exposure of temperatures in excess of 1200 °C. Reidite‐bearing grains with granular domains might signify swift quenching from temperatures close to 1200 °C. Grains subjected to these specific conditions therefore underwent partial zircon‐to‐reidite reversion, instead of full grain recrystallization. Based on our ZrSiO4 microstructural constraints, we decipher the grains evolution at specific P–T conditions related to different impact stages, offering further understanding of the behavior of ZrSiO4 during shock.

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Diffusionless Transformations

Abstract: The sections in this article are Introduction Classification and Definitions General Aspects of the Transformation Structural Relations Pre‐Transformation State Transformation Mechanisms Microstructures Shape Changes … Show more

Cited by 14 publications

References 52 publications

Diffusive and martensitic nucleation kinetics in solid-solid transitions of colloidal crystals

Diffusive and martensitic nucleation kinetics in solid-solid transitions of colloidal crystals

Effect of Thermomagnetic Treatment on Structure and Properties of Cu–Al–Mn Alloy

Exceptional preservation of reidite in the Rochechouart impact structure, France: New insights into shock deformation and phase transition of zircon

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