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

An overview of modern material science problems is presented for ultralightweight highmodulus commercial Al-Li-based alloys in historical retrospect. Numerous particular examples of the Soviet and Russian aviation whose various designs were made of these alloys confirm their successful innovative potential. The key regularities of multicomponent alloying are discussed for the master alloys and modern commercial Al-Li-based alloys of the latest generation; the features typical of their microstructures, phase composition, and properties formed during aging are analyzed. The main mechanisms of phase formation are generalized for standard thermal and thermomechanical treatments. Recent original achievements have been obtained in designing of unique structural and phase transformations in these commercial alloys by means of methods of severe plastic deformations followed by heat treatment and storage. Using the example of three Russian commercial alloys of last generation, the basic principles of creating and controlling an ultrafine-grained structure, the origin and growth of stable nanophases of various types and chemical composition that determine the physicomechanical properties of alloys are established. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.This work was performed within the framework of state task 122021000033-2 “Structure”

Effect of irradiation and subsequent aging on the structure of a B-1461 alloy of the Al-Cu-Li-Zn system after megaplastic deformation

The effect of Ar+ ion irradiation and subsequent prolonged aging on the microstructure and phase transformations in a B-1461 alloy (Al-Cu-Li-Zn-Mg-Zr-Sc) subjected to megaplastic deformation (MPD) has been studied by transmission electron microscopy. A mixed structure, consisting of nanocrystalline and nanofragmented regions has been found to form in the alloy upon MPD. Subsequent short-term Ar+ ion irradiation (E = 20 keV, j = 300 μA•cm-2, F = 1.9?1015 cm-2) forms dislocation tangles, increases the nonuniform distribution and the size of structural elements, as well as volume fraction of a T2-phase (Al3CuLi5) nano and submicrocrystals heterogeneously nucleated at boundaries. Structural changes are observed at a distance of ∼ 200 μm from the surface, which considerably exceeds the projective ion range (∼ 20 nm). The structure of the B-1461 alloy after MPD and subsequent irradiation under the above conditions is unstable. © 2019 IOP Publishing Ltd. All rights reserved.Russian Foundation for Basic Research, RFBR: 18-08-00942-AThis work was supported in part by RFBR grant No. 18-08-00942-A

The effect of ion irradiation (Ar+, e = 10 keV) on the nanocrystalline structure and the aging of the Al-Li-Cu-Zn-Mg-Zr-Sc alloy after megaplastic deformation

The effect of Ar+ ion irradiation on structural and phase transformations in a 1461 alloy (Al-Li-Cu-Mg) subjected to megaplastic deformationhas has been studied by transmission electron microscopy. Short-term irradiation (E = 10 keV, F = 2 × 1016 cm-2) has been established to form a low-energy recrystallized submicrocrystalline structure at a depth (∼200 μm), significantly exceeding the projective ion ranges (∼10 nm). The study confirms the important role of the radiation-dynamic effect during the ion irradiation of metastable media. The structural and phase transformations take place in the alloy at a depth of much higher than the projective ion ranges and at a higher rate compared with traditional thermal annealing. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 18-08-00942-AThis work was supported in part by RFBR grant № 18-08-00942-A

FEATURES OF SUBMICRO- AND NANO- CRYSTALLINE STRUCTURE IN AL-LI-ALLOYS UPON MEGA PLASTIC DEFORMATION

С помощью методов просвечивающей электронной микроскопии изучено влияние химического состава сплавов системы Al-Cu-Li на образование в них нанокристаллической структуры после мегапластической деформации кручением под высоким давлением и последующего отжига. Выявлено, что размерная стабильность зеренной структуры наноструктурированных сплавов обусловлена барьерным эффектом выделяющейся гетерогенно стабильной мелкодисперсной фазы T2.The effect of chemical composition on formation of nanocrystalline structure in Al-Cu-Li alloys subjected to severe plastic deformation by high-pressure torsion and subsequent annealing is investigated by methods of transmission electron microscopy. It has been shown that size stability of nanocrystalline structure is caused by the barrier effect of the finely heterogeneously dispersed stable T2-phases