Partition the total energy of Al3Ti to characterize the Al3Ti/Al interface properties: a first-principles study

Abstract

The geometric model of coplanar reciprocal lattice points (CRLPs) was used to predict the preferred orientation relationships (ORs) between the Al3Ti intermetallic particle and the Al matrix. The calculation result indicates that there exist two preferred ORs, i.e. (001)Al3Ti//(001)Al, [100]Al3Ti//[100]Al and (010)Al3Ti//(010)Al, [100]Al3Ti//[101¯]Al. The periodic models with a specific interface structure and surface slab models on a particular crystallographic plane were proposed to partition the total energy of the Al3Ti compound into its constituent atoms’ energies. The Ti and two kinds of Al atoms (Wyckoff notation 2b and 4d) possess the energy of -119.80325739 Ry, -5.09778518 Ry, and -5.03677683 Ry, respectively. Compared with the Al3Ti total energy of -269.94919247 Ry, the proposed energy partition scheme presents a satisfactory accuracy better than ∼10−7 Ry. Owing to the data of the atom's energy in the solid state, the definite value of surface energy can be obtained whether or not it is a stoichiometric or non-stoichiometric surface. The interface energy calculation, which was carried out on all the preferred ORs with all the possible atomic configurations, indicates that the energy-preferred interface possesses the orientation relationship of (001)Al3Ti//(001)Al, [100]Al3Ti//[100]Al. The atomic configuration is that the atoms on the surface of the Al slab face directly to atoms on the second layer of the Al3Ti slab with the Al-Ti terminated surface on account of its lowest interface energy of 0.005 J/m2. The predicted OR agrees well with the previously published experimental results, and the significantly lower interface energy explains the potency of the Al3Ti particle as a heterogeneous nucleation site in the aluminum solidification process.