title: Persistent medium-range order and anomalous liquid properties of Al(1-x)Cu(x) alloys.
abstract: The development of short-to-medium-range order in atomic arrangements has generally been observed in noncrystalline solid systems such as metallic glasses. Whether such medium-range order (MRO) can exist in materials at well above their melting or glass-transition temperature has been a long-standing important scientific issue. Here, using ab initio molecular dynamics simulations, we show that a novel, persistent MRO exists in liquid Al-Cu alloys near the composition of CuAl3. The correlated atomic motions associated with the MRO give rise to a substantially enhanced viscosity in the vicinity of the composition. The component of the MRO liquid state gradually decreases with increasing temperature, and it disappears above a crossover temperature T(LLC). The continuous liquid-liquid crossover through a percolationlike transition leads to a pronounced heat capacity peak at T(LLC).
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA. Joongoo.Kang@nrel.gov
authors.forename: Joongoo
authors.initials: J
authors.lastname: Kang
authors.forename: Junyi
authors.initials: J
authors.lastname: Zhu
authors.forename: Su-Huai
authors.initials: SH
authors.lastname: Wei
authors.forename: Eric
authors.initials: E
authors.lastname: Schwegler
authors.forename: Yong-Hyun
authors.initials: YH
authors.lastname: Kim