针对Al-Li合金中的复合沉淀相δ'/θ'/δ'存在的不同位相关系,采用第一性原理方法计算了不同界面结构的形成焓、界面能、解理功和理想解理强度,获得δ'/θ'/δ'在不同生长过程中的稳定界面结构。当θ'相包含奇数Cu层时,δ'/θ'采取反相(anti-phase) a / 2[110]结构；包含偶数Cu层时,δ'/θ'采取同相(in-phase) #2结构。且随着θ'相生长,2种位相通过沿界面[110]方向滑移a / 2实现。同时,δ'相将自发在θ'相上异质形核实现该稳定的δ'/θ'界面结构。基于Rose断裂模型,稳定界面结构拥有最高的黏合强度和理想解理强度。最后,基于界面间键合原子的晶体轨道重叠布居及键长分析,揭示了电子成键和结构稳定性的关系。表明界面间Al—Al键对结构稳定性起主导,且主要源自Al原子3p—3p轨道成键态贡献。

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.