Nucleation centers and wave schemes of martensite growth in iron alloys

Кащенко, М. П.; Vereshchagin, V. P.

doi:10.1007/bf00898530

Cited by 6 publications

(3 citation statements)

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“…Then the overcoming of a finite energy barrier will be promoted by the longitudinal displacement mode with wavelength λ 3 = 2λ 1 synchronized with the transverse mode. In our opinion, this is a dominant mechanism in the plane shuffle, resulting in the final sequence A α B α A α B α A α B α … Note that the existence of breather-type excitations with synchronized transverse and longitudinal displacements, which are responsible for the change of the plane positioning sequence, was suggested earlier (without concrete definition of wavelength values) [13].…”

Section: Short-wave Displacements Changing the Plane Positioning Sequmentioning

confidence: 62%

“…This seems to be a reason for the predetermination of the selection of DNC's with <110> γ and <112> γ lines that correspond to the DWP [1-3]. However, having produced a selected system of dislocations with lines Λ along one of the <111> γ directions for as-quenched martensite, one can obtain a strongly pronounced orientation effect: the occurrence of crystals with habituses of type (13) which are collinear with Λ and have no more than six orientations. For strain-induced martensite, the orientation effect can be enhanced by stretching austenite along the selected <111> γ direction .…”

Section: Expected Habituses and Dislocation Nucleation Centers For Asmentioning

confidence: 99%

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Mechanism of the fcc-bcc martensitic transformation with the fastest transformation of close-packed planes. I. The lattice parameter ratio and habitus planes

Kaschenko

Chaschina

2008

Russ Phys J

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536.421.1 In terms of the concepts of heterogeneous nucleation and the related driving wave process, a version of the dynamic theory of the formation of martensite crystals is stated in which the wave process initiates the fastest transformation of close-packed {111} γ atomic planes of a parent fcc phase into {110} α planes of a bcc phase. The lattice parameter ratio and the orientations of habit planes are analytically related with the elastic properties of the γ -phase. Quantitative estimation performed with the use of elastic moduli for an iron-nickel alloy yields habitus orientations close to {10 3 7} γ . An experiment is proposed to verify the theoretical predictions. A new pattern of the short-wave correction that finishes the fcc-bcc rearrangement is set forth.The growth of crystals in the (γ-α) fcc-bcc martensitic transformation is a fast process with strongly pronounced indications of the first-order transition. The nucleation is heterogeneous and the growth is controlled by a driving wave process (DWP). Recall [1, 2] that a DWP which forms a plate-shaped region bounded with habit planes (HP's), carries nearly plane and nearly homogeneous threshold deformation (of the tension-compression type) on the mesoscopic scale (of the order of the crystal thickness). As a result, the HP appears to be an invariant (or slightly distorted) plane. The wave normals n 1 and n 2 of the wave beams that describe, respectively, tensile deformation (ε 1 > 0) and compressive deformation (ε 2 < 0) in the superposition region are collinear to the eigenvectors ξ i (i = 1, 2) of the deformation tensor of the elastic field of a defect in the nucleation region (DWP inherits the information on the directions of ξ i ): n 1 || ξ 1 , n 2 || ξ 2 , n 1 ⊥ n 2 | n i | = | ξ i | = ||ξ⊥|||ξ|1.(1)These processes are sketched in Fig. 1. It can easily be shown [1−3] that the normal N w to a habitus plane that is related to the propagation of a driving wave is set by the kinematic relation N w || n 2 ± n 1 ae, ae = 2where v 1 and v 2 are the moduluses of the wave velocity. On the other hand, for a tension-compression deformation the normals to invariant planes are given by

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Section: Short-wave Displacements Changing the Plane Positioning Sequmentioning

confidence: 62%

Section: Expected Habituses and Dislocation Nucleation Centers For Asmentioning

confidence: 99%

Mechanism of the fcc-bcc martensitic transformation with the fastest transformation of close-packed planes. I. The lattice parameter ratio and habitus planes

Kaschenko

Chaschina

2008

Russ Phys J

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“…From Eq. (14) it follows that at θ = −π/2, the eigenvectors of the strain tensor are at angles of ±π/4 to the extra plane. This means that the extra plane for normals (9) coincides with the orientation of the habit plane.…”

mentioning

confidence: 98%

On the Applicability of the Concept of Control Wave Process to the B 2→R Martensitic Transformation in B 2 Titanium Nickelide Alloys

Кащенко

Чащина

2013

Russ Phys J

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Reactive vapor-phase dealloying-alloying turns oxides into sustainable bulk nano-structured porous alloys

Wei,

Ma,

Raabe

2024

Sci. Adv.

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For millennia, alloying has been the greatest gift from metallurgy to humankind: a process of mixing elements, propelling our society from the Bronze Age to the Space Age. Dealloying, by contrast, acts like a penalty: a corrosive counteracting process of selectively removing elements from alloys or compounds, degrading their structural integrity over time. We show that when these two opposite metallurgical processes meet in a reactive vapor environment, profound sustainable alloy design opportunities become accessible, enabling bulk nanostructured porous alloys directly from oxides, with zero carbon footprint. We introduce thermodynamically well-grounded treasure maps that turn the intuitive opposition between alloying and dealloying into harmony, facilitating a quantitative approach to navigate synthesis in such an immense design space. We demonstrate this alloy design paradigm by synthesizing nanostructured Fe-Ni-N porous martensitic alloys fully from oxides in a single solid-state process step and substantiating the critical kinetic processes responsible for the desired microstructure.

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Nucleation centers and wave schemes of martensite growth in iron alloys

Cited by 6 publications

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Mechanism of the fcc-bcc martensitic transformation with the fastest transformation of close-packed planes. I. The lattice parameter ratio and habitus planes

Mechanism of the fcc-bcc martensitic transformation with the fastest transformation of close-packed planes. I. The lattice parameter ratio and habitus planes

On the Applicability of the Concept of Control Wave Process to the B 2→R Martensitic Transformation in B 2 Titanium Nickelide Alloys

Reactive vapor-phase dealloying-alloying turns oxides into sustainable bulk nano-structured porous alloys

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