Influence of the microstructure on the void swelling of a 6061 aluminum alloy under irradiation

International audienceAluminum alloys are commonly used in nuclear research reactors, as there are known to be relatively neutron transparent, easy to machine and have a low γ-heating allowing to limit the temperature in core. Al-Mg-Si alloys benefit from a strong precipitation hardening after a specific thermal treatment (annealing, quenching and artificial ageing) pictured in figure 1. Extensive literature studies on annealing, ageing and its consequences on mechanical properties have been conducted but the quench has been poorly studied, as it is a general consent that the critical cooling rate is about 10°C /s. However, higher and lower speed may have a primary influence on the alloy behavior under irradiation.Using thick section specimens (98mm side cubes) and different fluids (air, oil, water), different microstructures and quench speeds have been produced. TEM samples from various quench rates were irradiated with a gold ion beam in order to observe the evolution of the microstructures and its influence on void swelling. Additional TEM specimens were irradiated with a triple ion beam in order to simulate reactor conditions (W for damage, Si and He to reproduce the transmutation of aluminum)