Grain-boundary free energy via thermodynamic integration

2006 ◽  
Vol 124 (6) ◽  
pp. 064707 ◽  
Author(s):  
Mark T. Lusk ◽  
Michael R. Fellinger ◽  
Paul D. Beale
Keyword(s):  
Free Energy ◽  
Grain Boundary ◽  
Thermodynamic Integration

Free Energy of the Σ = 11 (332) Tilt Grain Boundary in Silicon

1993 ◽  
Vol 126-128 ◽  
pp. 253-256 ◽  
Author(s):  
S. Mourelatos ◽  
N. Ralantoson ◽  
P. Delavignette ◽  
A. Hairie ◽  
F. Hairie ◽  
...  
Keyword(s):  
Free Energy ◽  
Grain Boundary ◽  
Tilt Grain Boundary

The Free Energy Simulation Approach to Grain Boundary Segregation In Cu-Ni

1990 ◽  
Vol 209 ◽  
Author(s):  
H. Y. Wang ◽  
R. Najafabadi ◽  
D. J. Srolovitz ◽  
R. Lesar
Keyword(s):  
Monte Carlo ◽  
Free Energy ◽  
Grain Boundary ◽  
Chemical Potential ◽  
Boundary Segregation ◽  
Configurational Entropy ◽  
Accurate Method ◽  
Increasing Temperature ◽  
Atomic Coordinates ◽  
Good Agreement

ABSTRACTA new, accurate method for determining equilibrium segregation to defects in solids is employed to examine the segregation of Cu to grain boundaries in Cu-Ni alloys. The results are in very good agreement with the ones given by Monte Carlo. This method is based upon a point approximation for the configurational entropy, an Einstein model for vibrational contributions to the free energy. To achieve the equilibrium state of a defect in an alloy the free energy is minimized with respect to atomic coordinates and composition of each site at constant chemical potential. One of the main advantages this new method enjoys over other methods such as Monte Carlo, is the efficiency with which the atomic structure of a defect, segregation and thermodynamic properties can be determined. The grain boundary free energy can either increase or decrease with increasing temperature due to the competition between energetic and configurational entropy terms. In general, the grain boundary free energy increases with temperature when the segregation is strongest.

Diffusion-Induced Grain Boundary Migration and Role of Defects

1993 ◽  
Vol 319 ◽  
Author(s):  
T.K. Chaki
Keyword(s):  
Free Energy ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Solute Concentration ◽  
Grain Boundary Migration ◽  
Thermally Activated ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Liquid Film Migration ◽  
Lattice Diffusivity

AbstractA model is presented to explain various aspects of diffusion-induced grain boundary migration (DIGM). The driving energies of DIGM are identified as the free energy of mixing and the interface free energy, the former being predominant in most cases of DIGM. The grain boundary migrates due to thermally activated motion of atoms across the interface under the influence of the driving energies. An expression for the velocity of migration is derived. It is shown that this depends parabolically on the solute concentration, in agreement with experimental observations in the case of liquid film migration (LFM), which is analogous to DIGM. Furthermore, the velocity is proportional to lattice diffusivity ahead of the boundary. Recent results of enhancement of DIGM by ion bombardment is explained by radiation-enhanced lattice diffusivity due to introduction of point defects by the ions. The model also explains that diffusion-induced recrystallization (DIR) is due to a free energy decrease associated with the transformation from the amorphous phase in the grain boundary layer to the crystalline phase.

scholarly journals Dynamics of grain boundary premelting

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Torabi Rad ◽  
G. Boussinot ◽  
M. Apel
Keyword(s):  
Free Energy ◽  
Steady State ◽  
Grain Boundary ◽  
Liquid Layer ◽  
Phase Field Model ◽  
Melting Process ◽  
State Growth ◽  
Curvature Driven ◽  
Multi Phase ◽  
Solid Liquid Interface

AbstractThe mechanical strength of a polycrystalline material can be drastically weakened by a phenomenon known as grain boundary (GB) premelting that takes place, owing to the so-called disjoining potential, when the dry GB free energy $$\sigma _{gb}$$ σ gb exceeds twice the free energy of the solid–liquid interface $$\sigma _{sl}$$ σ sl . While previous studies of GB premelting are all limited to equilibrium conditions, we use a multi-phase field model to analyze premelting dynamics by simulating the steady-state growth of a liquid layer along a dry GB in an insulated channel and the evolution of a pre-melted polycrystalline microstructure. In both cases, our results reveal the crucial influence of the disjoining potential. A dry GB transforms into a pre-melted state for a grain-size-dependent temperature interval around $$T_m$$ T m , such that a critical overheating of the dry GBs over $$T_m$$ T m should be exceeded for the classical melting process to take place, the liquid layer to achieve a macroscopic width, and the disjoining potential to vanish. Our simulations suggest a steady-state velocity for this transformation proportional to $$\sigma _{gb} -2 \sigma _{sl}$$ σ gb - 2 σ sl . Concerning the poly-crystalline evolution, we find unusual grain morphologies and dynamics, deriving from the existence of a pre-melted polycrystalline equilibrium that we evidence. We are then able to identify the regime in which, due to the separation of the involved length scales, the dynamics corresponds to the same curvature-driven dynamics as for dry GBs, but with enhanced mobility.

Sign in / Sign up

Export Citation Format

Share Document