General structural and dynamic characteristics beneficial to glass-forming ability of Fe-based glass-forming liquids

It is known that the relatively poor glass-forming ability (GFA) is a big problem for the development of Fe-based metallic glasses (MGs) and thus understanding the GFA-related structural and dynamic characteristics is significant. Using classical molecular dynamics (MD) simulations, the present work aims to discover the general GFA-related features in Fe-based liquids by the addition of large metallic (Ni) and small non-metallic (P) elements, respectively, into pure Fe melts. Simulation results demonstrate the better GFA of both the Fe80Ni20 and Fe20P20 liquids than that of pure Fe. Compared with pure Fe liquid, in both Fe80Ni20 and Fe20P20 glass-forming liquids, more ⟨0, 0, 12, 0⟩, ⟨0, 1, 10, 3⟩ and ⟨0, 1, 10, 2⟩ icosahedron-like clusters with slow dynamics form rapidly during cooling, accompanied with depressing ⟨0, 3, 6, 4⟩, ⟨0, 3, 6, 5⟩, ⟨0, 2, 8, 4⟩ and ⟨0, 4, 4, 6⟩ bcc-like clusters with faster dynamics. Also, the dynamic heterogeneity of Fe80Ni20 and Fe80P20 liquids experiences a more dramatic increase before glass transition. These findings reveal the general structural and dynamic characteristics in Fe-based glass-forming liquids beneficial to GFA and shed light on how to enhance GFA from the structural and dynamic origin.