The Structural Evolution of Al 86 Ni₉La₅ Glassy Ribbons during Milling at Room and Cryogenic Temperatures.

Melt-spun metallic Al86 Ni₉La₅ glassy ribbons solidified at different circumferential speeds ( S c ) were subjected to high-energy ball milling at room and cryogenic temperatures. Crystallization induced by milling was found in the Al86 Ni₉La₅ solidified at lower circumferential speed ( S c = 14.7 m/s), while the Al86 Ni₉La₅ with S c = 36.6 m/s kept amorphous. Besides, a trend of structural rejuvenation during milling process was observed, as the onset temperatures ( T x1 , T x2 ) and the crystallization enthalpies (Δ H ₁, Δ H ₂) first decreased and then increased along with the milling time. We explored the structural origin of crystallization by ab initio molecular dynamic simulations and found that the tricapped trigonal prism (TTP) Ni-centered clusters with a higher frequency in samples solidified at a lower cooling rate, which tend to link into medium-range orders (MROs), may promote crystallization by initiating the shear bands during milling. Based on the deformation mechanism and crush of metallic glasses, we presented a qualitative model to explain the structural rejuvenation during milling.