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

Abstract

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.