Zirconium aluminum alloy is added in some 7000 series alloys in
order to reduce the susceptibility of corrosion by tension.
The addition of Zr (in order to reach a 0.1 to 0.3% rate) is performed
to form a thin precipitate of intermetallic particles which suppresses
the recovery and the recrystallization. In other alloys, Zr is used
to increase the recrystallization temperature and the control of grain
structure in cast products.