Effect of 0.4 Wt% Yttrium Addition and Heat Treatment on the High-Temperature Compression Behavior of Cast AZ80

The effects of 0.4 wt% yttrium (Y) addition, annealing, and annealing + aging on the hot compression behavior of cast AZ80 were studied at strain rates between 10−4 and 10−2 s−1 and temperatures ranging between 573 and 673 K. The apparent activation energies of the as-cast AZ80 and AZ80 + 0.4Y were 122 and 182 kJ/mol, respectively. Shear bands formed in each alloys. Compared with the as-cast AZ80, more shear bands formed, and a larger volume of cracks initiated and propagated from the grain boundaries and shear bands in as-cast AZ80 + 0.4Y. In general, Y addition increased the peak stress at lower temperatures and higher strain rates. The annealed and annealed + aged alloys exhibited more shear bands and larger compressive peak stresses than their respective as-cast counterparts after compression at 573 K, 10−2 s−1. There were more shear bands in the annealed and annealed + aged AZ80 + 0.4Y compared with AZ80 after compression at 573 K, 10−2 s−1. Fine precipitates appeared in the shear bands of AZ80 + 0.4Y. The average width of the shear bands increased with increasing temperature and decreasing strain rate, and the angles of intersection between the different shear bands were approximately 90°.