Structural and Phase Transformations in Al–Li–Cu–Mg–Zr–Sc–Zn Alloy upon Storage after Megaplastic Deformation

Multicomponent Aging Al-Li-Based Alloys of the Latest Generation: Structural and Phase Transformations, Treatments, Properties, and Future Prospects

“…In the structure of the alloy 1461 subjected to HPT at n = 1, after 1 year of storage, regions of fragmented structures of different scales continued to coexist. The incompleteness of the recrystallization process was additionally confirmed by the high size dispersion of NC-and SMC grains and the preservation of a certain number of disjointed dipole boundaries and grains with nonequilibrium convex-concave boundaries [142].…”

“…It was established that when the alloys 1469 and 1461 deformed by HPT at n = 1 were then stored for 1 month [141,142], as a result of static recrystallization, a certain transformation of the deformed structure occurs, in result of which the proportion of recrystallized nanograins with an average size of 30-70 nm increased (cf. Figure 14).…”

“…After storage, the tendency to pronounced banding increased, which was clearly revealed in the dark-field images of the alloys (Figure 14b,e). One of the results of the formation of areas with an inhomogeneous unidirectional band substructure consisting of "bands" up to 100 nm thick was anisotropy in the distribution of nanofragments and nanograins along noncrystallographic directions corresponding to the prevailing direction of rotational mass transfer at SPD [142].…”

“…The performed analysis made it possible to establish that the character of the nucleation and the volume fraction of the T 2 phase, formed after SPD in the form of disperse particles along the boundaries of the fragments and grains in the alloys 1461 and 1469, virtually did not change during the storage of alloys for 1 month, and the particles of the T 2 phase remained in the form of disperse precipitates with a diameter of 5-10 nm [141,142]. For the alloy 1469, attention is drawn to the appearance of a diffraction contrast of the ripple type, typical of the occurrence of intragrain mechanism of the formation of the δ' phase in these alloys.…”