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 of δ′ (Al

3

Li) and δ′(Al

3

Li)/Al

3

Sc core–shell structures with non–equilibriu

m composition; the coherent and semi–coherent interfaces of θ′(Al

2

Cu)/α–Al and the segregation behavior of Cu at the interfaces; the origin of the relationships including “in–phase” and “anti–phase” for opposite δ' phases in the δ′/θ′/δ′ composite precipitation; and various crystal structure models of T1 (Al

2

CuLi). In Al–Li–Cu–Mg system: the interface of S(Al

2

CuMg)/α–Al; the good resistance of Ω(Al

2

Cu) phases to grain coarsening and the nucleation induced by vacancy. In the Al–Li–Cu–Mg–Si system: the competitions for σ(Al

5

Cu

6

Mg

2

) – S' and σ–Ω due to non–component Si and Ag atoms; and phase transition from Q(Al

3

Cu

2

Mg

9

Si

7

) to B'(Al

3

Mg

9

Si

7

) 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.