7xxx aluminum series Al alloy Al alloy 7075-T6 Al3(Sc,Zr) particles SLM Technology: general issues VPPA activation energy ageing aluminium aluminium alloy aluminium alloys aluminum alloy AA5083 annihilation of positrons artificial pits asymmetric weld auxetic structures bimodal microstructure characterization methods corrosion crack initiation differential scanning calorimetry (DSC) early precipitation stages extrusion fatigue heat treatment high-strength aluminum homogenization annealing intermetallic phases laser induced arc hybrid welding