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Diffusion in Ni–Zr Melts: Insights from Statistical Mechanics and Atomistic Modeling. ADVANCED THEORY AND SIMULATIONS 2018. [DOI: 10.1002/adts.201800109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Sabochick MJ, Lam NQ. Atomistic Simulation of Radiation-Induced Amorphization of the B2 Ordered Intermetallic Compound NiTi. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-201-387] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractAmorphization of the B2 intermetallic compound NiTi under electron irradiation has been investigated using molecular dynamics. The effect of irradiation was simulated using two processes: 1) Ni and Ti atoms were exchanged, resulting in chemical disorder, and 2) Frenkel pairs were introduced, leading to the formation of stable point defects and also chemical disorder upon mutual recombination of interstitials and vacancies. After ∼0.1 exchanges per atom, the first process resulted in an energy increase of approximately 0.11 eV/atom and a volume increase of 1.91%. On the other hand, after introducing ∼0.5 Frenkel pairs per atom, the second process led to smaller increases of 0.092 eV/atom in energy and 1.43% in volume. The calculated radial distribution functions (RDFs) were essentially identical to each other and to the calculated RDF of a quenched liquid. The structure factor, however, showed that long-range order was still present after atom exchanges, while the introduction of Frenkel pairs resulted in the loss of long-range order. It was concluded that point defects are necessary for amorphization to occur in NiTi, although chemical disorder alone is capable of storing enough energy to make the transition possible.
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Koike J, Okamoto PR, Rehn LE, Bhadra R, Grimsditch MH, Meshh M. Irradiation-Induced Amorphization and Elastic Shear Instability in Intermetallic Compounds. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-157-777] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTPreviously we reported a substantial (∼ 50 %) decrease in shear modulus prior to amorphization in Kr irradiated Zr3Al, and proposed that amorphization is triggered when the crystalline lattice becomes unstable against shear stress. In the present work, the relation between amorphization and shear elastic instability has been investigated in two additional compounds (FeTi and NiAl) during room temperature irradiation with 1.7-MeV Kr+. A shear modulus was measured using Brillouin scattering; structural information was obtained in situ in a high voltage electron microscope interfaced to a tandem accelerator.During irradiation of FeTi, chemical disordering and a large (∼40 %) decrease of shear modulus were observed, and an amorphous phase developed subsequently. In contrast, NiAl remained crystalline and chemically ordered during irradiation, and exhibited only a ∼ 10 % decrease in shear modulus. Hence, these two results provide further support that a shear instability triggers irradiation-induced amorphization. The shear instability mechanism may also apply to other solid-state amorphization techniques, e.g. hydrogen charging and mechanical deformation.
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Delogu F. Identification and characterization of potential shear transformation zones in metallic glasses. PHYSICAL REVIEW LETTERS 2008; 100:255901. [PMID: 18643675 DOI: 10.1103/physrevlett.100.255901] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 04/09/2008] [Indexed: 05/26/2023]
Abstract
The stability of local atomic configurations in a Ni-Zr metallic glass is studied by molecular dynamics. It is shown that individual atom displacements induce irreversible atomic rearrangements under different glass relaxation, temperature, and strain conditions. The number of regions with an unstable topology depends on the glass relaxation degree. Their time evolution is governed by thermal activation, the activation energy decreasing with elastic strain. It is also shown that unstable regions are located in correspondence of shear transformation zones operating under plastic deformation.
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Affiliation(s)
- Francesco Delogu
- Dipartimento di Ingegneria Chimica e Materiali, Università di Cagliari, piazza d'Armi, I-09123 Cagliari, Italy.
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Delogu F. Atomic mobility and strain localization in amorphous metals. PHYSICAL REVIEW LETTERS 2008; 100:075901. [PMID: 18352569 DOI: 10.1103/physrevlett.100.075901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Indexed: 05/26/2023]
Abstract
Molecular dynamics simulations are employed to investigate the atomic mobility in Ni(50)Zr(50) amorphous alloys under both static conditions and shearing. Diffusion occurs under static conditions via cooperative stringlike motion involving atoms with large volumes. Atomic mobility is instead governed by rearrangements localized in shear transformation zones (STZs) under shearing. Local atomic volume plays in both cases a key role, the atomic ensembles involved in diffusion and STZ activity being strongly correlated.
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Affiliation(s)
- Francesco Delogu
- Dipartimento di Ingegneria Chimica e Materiali, Università di Cagliari, piazza d'Armi, I-09123 Cagliari, Italy.
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Zemlin F, Schuster R, Beckmann E, Carrascosa JL, Valpuesta JM, Ertl G. Stress-induced recrystallization of a protein crystal by electron irradiation. Nature 1999; 399:51-4. [PMID: 10331388 DOI: 10.1038/19947] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ordering of a system of particles into its thermodynamically stable state usually proceeds by thermally activated mass transport of its constituents. Particularly at low temperature, the activation barrier often hinders equilibration--this is what prevents a glass from crystallizing and a pile of sand from flattening under gravity. But if the driving force for mass transport (that is, the excess energy of the system) is increased, the activation barrier can be overcome and structural changes are initiated. Here we report the reordering of radiation-damaged protein crystals under conditions where transport is initiated by stress rather than by thermal activation. After accumulating a certain density of radiation-induced defects during observation by transmission electron microscopy, the distorted crystal recrystallizes. The reordering is induced by stress caused by the defects at temperatures that are low enough to suppress diffusive mass transport. We propose that this defect-induced reordering might be a general phenomenon.
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Affiliation(s)
- F Zemlin
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
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Gutiérrez G, Kiwi M, Ramírez R. Amorphization in the vicinity of a grain boundary: A molecular-dynamics approach. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:11701-11705. [PMID: 9984960 DOI: 10.1103/physrevb.54.11701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chakk Y, Berger S, Weiss BZ, Brook-Levinson E. Solid state amorphization by mechanical alloying—An atomistic model. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0956-7151(94)90433-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Mura P, Demontis P, Suffritti GB, Rosato V. Simulation of growth of Ni-Zr interfacial amorphous regions under nonequilibrium conditions. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:2850-2857. [PMID: 9976527 DOI: 10.1103/physrevb.50.2850] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Zhou GF, Bakker H. Atomic disorder and phase transformation in intermetallic compounds of the type T3X2 (T=Ni,Fe,Mn; X=Sn,Ge) by mechanical milling. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:12507-12518. [PMID: 10010151 DOI: 10.1103/physrevb.49.12507] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Rey C, Gallego LJ, García-Rodeja J, Alonso JA, Iñiguez MP. Molecular-dynamics study of the binding energy and melting of transition-metal clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:8253-8262. [PMID: 10007016 DOI: 10.1103/physrevb.48.8253] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Cleri F, Rosato V. Tight-binding potentials for transition metals and alloys. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:22-33. [PMID: 10006745 DOI: 10.1103/physrevb.48.22] [Citation(s) in RCA: 457] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Koike J. Elastic instability of crystals caused by static atom displacement: A mechanism for solid-state amorphization. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:7700-7704. [PMID: 10004776 DOI: 10.1103/physrevb.47.7700] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Li M, Johnson WL. Instability of metastable solid solutions and the crystal to glass transition. PHYSICAL REVIEW LETTERS 1993; 70:1120-1123. [PMID: 10054291 DOI: 10.1103/physrevlett.70.1120] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Weissmann M, Ramírez R, Kiwi M. Molecular-dynamics model of interface amorphization. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:2577-2583. [PMID: 10003936 DOI: 10.1103/physrevb.46.2577] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Massobrio C, Pontikis V. Percolation model for elastic softening in intermetallic compounds during solid-state amorphization. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:2484-2487. [PMID: 10001774 DOI: 10.1103/physrevb.45.2484] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Di LM, Bakker H, Tamminga Y. Mechanical attrition and magnetic properties of CsCl-structure Co-Ga. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 44:2444-2451. [PMID: 9999813 DOI: 10.1103/physrevb.44.2444] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Sabochick MJ, Lam NQ. Radiation-induced amorphization of ordered intermetallic compounds CuTi, CuTi2, and Cu4Ti3: A molecular-dynamics study. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 43:5243-5252. [PMID: 9997916 DOI: 10.1103/physrevb.43.5243] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Massobrio C, Pontikis V, Martin G. Molecular-dynamics study of amorphization by introduction of chemical disorder in crystalline NiZr2. PHYSICAL REVIEW. B, CONDENSED MATTER 1990; 41:10486-10497. [PMID: 9993456 DOI: 10.1103/physrevb.41.10486] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Sabochick MJ, Lam NQ. Amorphization of crystalline CuTi: Roles of chemical disordering and nonequilibrium lattice defects. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0956-716x(90)90202-r] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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