Structural features of aluminium alloy 1441 irradiated by Ar+ ions

Using electron microscopy it was found that irradiation of clad cold-worked specimens made of commercial aluminium-lithium alloy 1441 by the Ar+ ions of energy 40 keV at low doses of irradiation (1015 cm−2, irradiation time 1 s, T < 70 °C) and ion-current density of about 100 µA/cm2 results in the transformation of the cellular structure formed in the alloy under deformation. As the dose of irradiation is increased up to 1016 cm−2, a transition from a cellular to a subgrain structure close to a polygonal one is observed. The efficiency of the process is increased with ion-current density. Furthermore, under ion irradiation at increased ion-current densities, the β′(Al3Zr) and Al8Fe2Si particles present in the deformed alloy dissolve, and disperse particles of a new Al2LiMg phase of platelet shape are formed. The changes in the dislocation structure and phase composition in alloy 1441 are observed several seconds after irradiation not only in the surface layer adjacent to the ion incorporation band but also through the thickness of the specimen tens of thousands times greater than ion projective ranges.