High-angle annular dark-field scanning transmission electron micrograph (STEM) of a nanoscale precipitate of zinc (Zn), magnesium (Mg) and copper (Cu) in an advanced experimental aluminium (Al) alloy. The formation of precipitates in aluminium alloys increases their strength. Precipitation hardening, or age hardening, is achieved by heating the alloy. This is an Al-Zn-Mg-Cu alloy, which is widely used in aerospace applications due to its high strength to weight ratio and good weldability.