Dislocation-Pairing Transitions in Hot Grain Boundaries

Olmsted, David L.; Buta, Dorel; Adland, Ari; Foiles, Stephen M.; Asta, Mark; Karma, Alain

doi:10.1103/physrevlett.106.046101

Cited by 69 publications

(62 citation statements)

References 22 publications

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“…44), this model has been shown to predict reasonable values of solid-liquid interfacial energy 44,54 and GB energies 46 , despite the uncontrolled truncation of many other sets of reciprocal lattice vectors. It has also proven capable of reproducing a subtle dislocation-pairing GB structural transition at high homologous temperatures 23 , previously evidenced in a 2D PFC study of GB premelting 29 , and also observed in MD simulations 23 . However, the only two PFC studies of GB premelting to date have remained qualitative 28,29 .…”

Section: Introductionmentioning

confidence: 99%

“…(23) shows that the renormalized grand potential of the liquid has an ultraviolet divergence that requires keeping k max finite. Next, to estimate what this cutoff should be, we compare ∆Ω eq to the barrier height of the double-well potential between solid and liquid.…”

Section: B Short-wavelength Noise Cutoffmentioning

confidence: 99%

“…Hence, a more accurate prediction of when a GB will be wet or dry has been obtained in PFC simulations by using the wetting condition ∆γ > 0 in conjunction with a value of γ gb (T M ) that takes into account this elastic softening 29 . The extension of this approach to MD simulations of Fe for symmetric [001] tilt GBs has yielded reasonably good predictions of which GBs will be fully wet or dry over a complete range of misorientation 23 . This study also associated departures from this prediction to the existence of a dislocation-pairing transition, which provides an additional means for the GB to lower its free-energy, distinct from elastic softening.…”

Section: Introductionmentioning

confidence: 99%

“…Theoretical approaches include discrete lattice models 17 and molecular dynamics (MD) simulations [18][19][20][21][22][23] , as well as conventional phase-field models [24][25][26][27] , which either exploit an orientational order parameter 24,25 or multiple phase-fields 26,27 to distinguish between grains, and the phase-field-crystal (PFC) method 28,29 , which resolves the crystal density field on an atomic scale and hence naturally models crystal defects such as isolated dislocations and GBs.…”

Section: Introductionmentioning

confidence: 99%

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Phase-field-crystal study of grain boundary premelting and shearing in bcc iron

et al. 2013

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We use the phase-field-crystal (PFC) method to investigate the equilibrium premelting and nonequilibrium shearing behaviors of [001] symmetric tilt grain boundaries (GBs) at high homologous temperature over the complete range of misorientation 0 < θ < 90 • in classical models of bcc Fe. We characterize the dependence of the premelted layer width W as a function of temperature and misorientation. In addition, we compute the thermodynamic disjoining potential whose derivative with respect to W represents the structural force between crystal-melt interfaces due to the spatial overlap of density waves. The disjoining potential is also computed by molecular dynamics (MD) simulations, for quantitative comparison with PFC simulations, and coarse-grained amplitude equations (AE) derived from PFC that provide additional analytical insights. We find that, for GBs over an intermediate range of misorientation (θmin < θ < θmax), W diverges as the melting temperature is approached from below, corresponding to a purely repulsive disjoining potential, while for GBs outside this range (θ < θmin or θmax < θ < 90 • ), W remains finite at the melting point. In the latter case, W corresponds to a shallow attractive minimum of the disjoining potential. The misorientation range where W diverges predicted by PFC simulations is much smaller than the range predicted by MD simulations when the small dimensionless parameter ǫ of the PFC model is matched to liquid structure factor properties. However it agrees well with MD simulations with a lower ǫ value chosen to match the ratio of bulk modulus and solid-liquid interfacial free-energy, consistent with the amplitude-equation prediction that θmin and 90 • − θmax scale as ∼ ǫ 1/2 . The incorporation of thermal fluctuations in PFC is found to have a negligible effect on this range. In response to a shear stress parallel to the GB plane, GBs in PFC simulations exhibit coupled motion normal to this plane or sliding. Furthermore, the coupling factor exhibits a discontinuous change as a function of θ that reflects a transition between two coupling modes. Sliding is only observed over a range of misorientation that is a strongly increasing function of temperature for T /TM ≥ 0.8 and matches roughly the range where W diverges at the melting point. The coupling factor for the two coupling modes is in excellent quantitative agreement with previous theoretical predictions [J. W. Cahn, Y. Mishin, and A. Suzuki, Acta Mater. 54, 4953 (2006)].

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Section: Introductionmentioning

confidence: 99%

Section: B Short-wavelength Noise Cutoffmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phase-field-crystal study of grain boundary premelting and shearing in bcc iron

et al. 2013

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“…On the theoretical side we mention in particular discrete lattice models 17 as well as molecular dynamics (MD) simulations [18][19][20][21][22][23] . Several continuum descriptions have been pushed forward, including those based on phase field models [24][25][26][27] with either an orientational order parameter 24,25 or multiorder parameter models 26,27 ; these order parameters are needed to distinguish between the different grain orientations.…”

Section: Introductionmentioning

confidence: 99%

Structural short-range forces between solid-melt interfaces

Spatschek

Adland

2013

Phys. Rev. B

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We predict the structural interaction of crystalline solid-melt interfaces using amplitude equations which are derived from classical density functional theory or phase-field-crystal modeling. The solid ordering decays exponentially on the scale of the interface thickness at solid-melt interfaces; the overlap of two such profiles leads to a short range interaction, which is mainly carried by the longest-range density waves, which can facilitate grain boundary premelting. We calculate the tail of these interactions, depending on the relative translation of the two crystals fully analytically and predict the interaction potential, and compare it to numerical simulations. For grain boundaries the interaction is predicted to decay twice faster as for two crystals without misorientation.

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Plastic Deformation by Grain Boundary Motion: Experiments and Simulations

Molodov

2013

Microstructural Design of Advanced Engineering Materials

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Dislocation-Pairing Transitions in Hot Grain Boundaries

Cited by 69 publications

References 22 publications

Phase-field-crystal study of grain boundary premelting and shearing in bcc iron

Phase-field-crystal study of grain boundary premelting and shearing in bcc iron

Structural short-range forces between solid-melt interfaces

Plastic Deformation by Grain Boundary Motion: Experiments and Simulations

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