Al(f.c.c.):Al3Sc(L12) interphase boundary energy calculations

Abstract

AbstractÐThese calculations assess the applicability of classical nucleation theory to the reaction f.c.c. 4 L1 2 occurring in dilute Al±Sc alloys. The orientation and temperature dependence of the energies of coherent Al(f.c.c.):Al 3 Sc(L1 2 ) interphase boundaries were studied using atomistic simulation and a low temperature expansion (LTE) of the grand potential. Embedded atom method potentials were developed for both sets of calculations. Atomistic 0 K results for the anisotropy of the interphase boundary enthalpy gave g (100) <g (110) <g (111) with values of 32.5, 51.3 and 66.3 mJ/m 2 , respectively. LTE calculations of the excess grand potential of the (100) interface predicted a nearly temperature independent interfacial energy below 400 K that decreased modestly above 400 K. Monte Carlo (MC) simulations produced a compositional di useness of about 4 atomic layers separating the two bulk phases. Because the spatial extent of this region is very similar to the classically determined critical nucleus dimensions extracted from nucleation rate data, it is concluded that critical nuclei of Al 3 Sc are most likely of nonclassical design at high undercooling. # 1998 Acta Metallurgica Inc.

Nucleation ofAl3ZrandAl3Clouet1, Nastar2, Sigli3 2004Phys. Rev. B1335930View full textAdd to dashboardCite

“…This could explain too why the interface free energies we obtain are decreasing more rapidly with temperature especially in the [111] direction 51 . Hyland et al 52 also calculated interface free energies with an empirical potential for Al-Sc, but the energies they obtained are really low compared to ours and Asta's ones as well as compared to the isotropic interface free energy they measured 22 . Some of the discrepancy can be due to relaxations of atomic positions which are considered in their study and are missing in our.…”

Atomistic modeling of interfaces and their impact on microstructure and properties

“…[313][314][315][316][317][318]). The second approach employs grand-canonical MC simulations with interatomic potentials [104,319,320]. An example of an equilibrium composition profile calculated by this approach for an Ni/Ni 3 Al (1 0 0) interface at 700 K is shown in Fig.…”

Nanoscale structural evolution of Al3Sc precipitates in Al(Sc) alloys

“…Hyland et al [23] calculated, using Embedded Atom Method (EAM) potentials, 33, 51 and 78 mJ/m 2 for the energies at 0 K of the {100}, {110} and {111} interfaces, respectively. Using these interfacial energies, a Wulff construction shows that the small Al 3 Sc precipitates should be cubic with {100} facets.…”