Correlation between structure and glass-forming ability in Al86Ni14-xLax(x = 3,5,9) alloys: An ab initio molecular dynamics study

The correlation of atomic and electronic structures with glass-forming ability (GFA) in Al86Ni14-xLax (x = 3,5,9 at.%) alloys were systematically investigated via ab initio molecular dynamics simulations for understanding the mechanism of GFA in Al-based alloys. The obtained glass transition temperatures indicate that GFA is better in Al86Ni9La5 alloy, consistent with experimental measurements. In contrast to most other alloy systems where topological order and atomic packing efficiency are key to GFA, in Al-based alloys the chemical short-range order around Al atoms play more important role in GFA. It is revealed that chemically random distribution of Al atoms favors GFA. Meanwhile, Ni and La atoms are more chemically repulsed and preferred to Al atoms, respectively. Moreover, the electronic structure calculations demonstrate that the Al-3p and Ni-3d electrons are strongly hybridized, which is found to be critical in determining Fermi surfaces and GFA in Al86Ni14-xLax (x = 3,5,9) alloys. Taken the hybridization effect into account, the coincidence between good GFA and the local minimum of the electronic density of states at the Fermi level is obtained and verified for the first time by ab initio calculations. This finding provides new physical understanding for designing better Al-based bulk MGs.