Disjoining potential and grain boundary premelting in binary alloys

Hickman, J.; Mishin, Y.

doi:10.1103/physrevb.93.224108

Cited by 29 publications

(36 citation statements)

References 73 publications

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“…5(b)) and over-estimates in the Ag-rich solid solution ( Fig. 5(c)) [30]. At the temperature of 1000 K, the di↵erence between V and V ⇤ is 20 to 30 %, which is not as large as in Ni-Al at 700 K but still significant.…”

Section: Resultsmentioning

confidence: 87%

Thermodynamics of Cottrell atmospheres tested by atomistic simulations

Cahn

2016

Acta Materialia

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Solute atoms can segregate to elastically deformed lattice regions around a dislocation and form an equilibrium distribution called the Cottrell atmosphere. We compare two approaches to describe Cottrell atmospheres. In the Eshelby theory, the solid solution is represented by a composite material obtained by insertion of misfitting elastic spheres (solute atoms) into an elastic matrix (solvent). The theory proposed by Larché and Cahn (LC) treats the solution as an elastic continuum and describes elasto-chemical equilibrium using the concept of open-system elastic coe cients. The two theories are based on significantly di↵erent concepts and diverge in some of their predictions, particularly regarding the existence of screening of dislocation stress fields by atmospheres. To evaluate predictive capabilities of the two theories, we perform atomistic computer simulations of Al segregation on a dislocation in Ni. The results confirm the existence of hydrostatic stress screening in good agreement with the LC theory. The composition field is also in much better agreement with the LC prediction than with the Eshelby theory. However, the simulations confirm the logarithmic divergence of the total amount of solute segregation as expected from the Eshelby theory, whereas the LC theory predicts the total segregation to be zero. Several other aspects of the two theories are analyzed. Possible non-linear extensions of the LC theory are outlined.

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Section: Resultsmentioning

confidence: 87%

Thermodynamics of Cottrell atmospheres tested by atomistic simulations

Cahn

2016

Acta Materialia

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“…The DFT energies from the OQMD database [26] were used in the fitting process while the energies from AFLOW [25,56] are included to show the scatter of the DFT calculations. approximation as in the previous work [37][38][39][40][41]. In this approximation, the classical harmonic free energy is added to the potential energy of the system and the total free energy is minimized at the chosen reference temperature.…”

Section: Testing Of the Binary Ni-cr Potentialmentioning

confidence: 99%

Angular-dependent interatomic potential for the binary Ni–Cr system

Howells

2018

Modelling Simul. Mater. Sci. Eng.

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A new interatomic potential has been developed for the Ni-Cr system in the angular-dependent potential (ADP) format by fitting the potential parameters to a set of experimental and first-principles data. The ADP potential reproduces a wide range of properties of both elements as well as binary alloys with reasonable accuracy, including thermal and mechanical properties, defects, melting points of Ni and Cr, and the Ni-Cr phase diagram. The potential can be used for atomistic simulations of solidification, mechanical behavior and microstructure of the Ni-based and Cr-based phases as well as two-phase alloys.

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“…Consequently, heating the boundary to 800ºC leaves the boundary intact, possibly with increased disorder. Mishin and co-workers showed in a series of studies on Cu-Ag GBs that increasing temperature, but also increasing Ag solute excess can significantly influence how ordered a GB is referred to the perfect bulk lattice [39][40][41][42]. At such high temperatures, Ag atoms are going almost completely in solid solution and diffuse from the surface through the bulk and along the boundary creating a Ag concentration gradient.…”

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Segregation-Induced Nanofaceting Transition at an Asymmetric Tilt Grain Boundary in Copper

Peter¹,

Frolov²,

Duarte³

et al. 2018

Phys. Rev. Lett.

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We show that chemistry can be used to trigger a nanofaceting transition. In particular, the segregation of Ag to an asymmetric tilt grain boundary in Cu is investigated. Aberration-corrected electron microscopy reveals that annealing the bicrystal results in the formation of nanometer-sized facets composed of preferentially Ag-segregated symmetric Σ5f210g segments and Ag-depleted f230g=f100g asymmetric segments. Our observations oppose an anticipated trend to form coarse facets. Atomistic simulations confirm the nanofacet formation observed in the experiment and demonstrate a concurrent grain boundary phase transition induced by the anisotropic segregation of Ag.

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Disjoining potential and grain boundary premelting in binary alloys

Abstract: Many grain boundaries (GBs) in crystalline materials develop highly disordered, liquid-like structures at high temperatures. In alloys, this premelting effect can be fueled by solute segre-

Cited by 29 publications

References 73 publications

Thermodynamics of Cottrell atmospheres tested by atomistic simulations

Thermodynamics of Cottrell atmospheres tested by atomistic simulations

Angular-dependent interatomic potential for the binary Ni–Cr system

Segregation-Induced Nanofaceting Transition at an Asymmetric Tilt Grain Boundary in Copper

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