Hydrogen-induced dynamic slowdown of metallic glass-forming liquids*

Abstract

Dynamics of hydrogen doped Cu50Zr50 glass-forming liquids are investigated by using the newly developed modified embedded atomic method (MEAM) potential based on molecular dynamics simulations. We find that the doping of hydrogen atoms slows down the relaxation dynamics, reduces the fragility of supercooled melts, and promotes the occurrence of glass transitions. The dynamic slowdown is suggested to be closely related to the effect of hydrogen atoms on locally ordered structure of melts. With increasing concentration of hydrogen, the five-fold symmetry associated with Cu- and Zr-centered polyhedrons is lowered, on the other hand, the local order featuring metal hydrides is enhanced. The latter dominates the dynamic behaviors of glass-forming liquids, especially for Zr atoms, and results in the dynamic slowdown.

Unveiling the early stage evolution of local atomic structures in the crystallization process of a metallic glass

“…Various unique internal structures of MGs underlie their interesting properties, which render MGs potentially useful for distinct applications. [22][23][24][25] For the excellent mechanical properties of glasses with nanocrystalline inclusions and as well fundamental meanings to solid state physics, numerous studies have been conducted to comprehend how amorphous alloys crystallize at nanoscales. However, due to the lack of directly time-resolved data of atomic structure evolutions at the early stage of crystallization, clear pictures of how localized atomic structures rearranging themselves, developing original translational symmetry, and eventually forming nanocrystals with three-dimensional (3D) periodicity remain less well-understood at present.…”