铝锂合金纳米析出相结构与性能综述

Structures and Properties of Nano–Precipitates in Al–Li Alloys

纳米析出相种类、大小、形状、分布以及析出序列的调控是理解和设计第3、4代铝锂合金的基础。总结了铝锂合金中典型的Cu、Mg、Ag、Si合金元素作用下所产生的纳米析出相。重点介绍了Al-Li-Cu系中的δ′(Al3Li)相以及δ′(Al3Li)/Al3Sc核壳结构非平衡成分的稳定性问题、θ′(Al2Cu)/α-Al共格、半共格界面结构以及界面处的Cu元素偏析行为、δ′/θ′/δ′复合沉淀相中对立δ′相的“同相”和“反相”的位相关系起因,以及T1(Al2CuLi)的多种晶体结构模型;Al-Li-Cu-Mg系中的S(Al2CuMg)相与基体的界面结构、Ω(Al2Cu)相的抗粗化以及空位诱导的形核起源;Al-Li-Cu-Mg-Si系中的σ(Al5Cu6Mg2)-S′、σ-Ω由Si、Ag原子造成的竞争关系以及Q(Al3Cu2Mg9Si7)相中存在的本征点缺陷模型实现与B′(Al3Mg9Si7)的相互转变。结合X射线衍射、高分辨透射电子显微镜像、高角环形暗场扫描透射电子显微镜像以及第一性原理理论计算方法,为理解纳米沉淀相的性能提供启发。

The structure and performance of the third and fourth generation Al-Li alloys depend on the type,size,shape,distribution and sequence of the nano-precipitates within them.In this review paper,typically nano-precipitates generated by additions of Mg,Ag,Si,and Mn elements were reported.In particular,in Al-Li-Cu system:stabilities ofδ′(Al3Li)andδ′(Al3Li)/Al3Sc core-shell structures with non-equilibrium composition;the coherent and semi-coherent interfaces ofθ′(Al2Cu)/α-Al and the segregation behavior of Cu at the interfaces;the origin of the relationships including“in-phase”and“anti-phase”for oppositeδ'phases in theδ′/θ′/δ′composite precipitation;and various crystal structure models of T1(Al2CuLi).In Al-Li-Cu-Mg system:the interface of S(Al2CuMg)/α-Al;the good resistance ofΩ(Al2Cu)phases to grain coarsening and the nucleation induced by vacancy.In the Al-Li-Cu-Mg-Si system:the competitions forσ(Al5Cu6Mg2)-S'andσ-Ωdue to non-component Si and Ag atoms;and phase transition from Q(Al3Cu2Mg9Si7)to B'(Al3Mg9Si7)because of the intrinsic point defect in Q.By using X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),and first-principle calculations,it is able to provide inspiration for us to understand the performances of these nano precipitations.