Enhanced mechanical properties due to nanocrystallization by isothermal annealing in Al₈₅Ni₉Er₆ glassy alloy

In present work, isothermal annealing has been used to enhance the mechanical properties of Al₈₅Ni₉Er₆ glassy alloy. Compared to 3.55 GPa, the hardness of the melt-spun alloy, the hardness of the alloy after annealed for 60 min and 90 min increased to 5.7 GPa and 5.55 GPa, respectively. The appearance of many fcc-Al nanocrystals lead to significant hardening. During the annealing, the nanocrystal size does not change much, but nanocrystal number increases between 50 min and 90 min at 519 K, which inferred that the mechanical properties of Al-based metallic glasses may be influenced by crystal number more than crystal size. The mechanical properties evolution of the metallic glass with the annealing time is due to combined effects of variations of the free volume and fcc-Al nanocrystals in the amorphous matrix.