Al-Li 合金中 δ′/θ′/δ′复合沉淀相结构演化及稳定性的第一性原理探究

To obtain the stable interfacial structures of a δ'/θ'/δ' nanocomposite precipitate in Al-Li alloys, the formation enthalpy, interfacial energy, cleavage work, and ideal cleavage strength are calculated for all constructed interface structures at different growth stages. Thus, the results indicate that the δ'/ θ'/δ' adopts an anti-phase a / 2[110] interfacial structure when the θ' phase contains an odd number of Cu layers; conversely, it adopts an in-phase #2 interfacial structure. As θ' increases, these two structures transform by slipping a / 2 along the [110] direction. Simultaneously, the heterogeneous nucleation of δ' achieves the stable δ'/θ' interfacial structure spontaneously. Under Rose’s fracture model, this stable interfacial structure also possesses the highest bonding strength and the largest ideal cleavage strength. Finally, the crystal orbital Hamilton population and bond length analyses reveal the relation between the electronic bonding and structural stability. It is shown that the inter Al—Al interactions significantly influence the structural stability, which mainly originated from the 3p—3p orbital-pair contributions.