Molecular dynamics study of structural evolution of aluminum during rapid quenching under different pressures

We present a molecular dynamics simulation for liquid Al during the rapid quenching under different pressures. The pair analysis technique and the probabilities of bond energy distribution of inherent structures have been employed to reveal the structural characteristics of liquid and glassy Al. During the liquid-glass quenching process, the bond pairs representing the degree of icosahedral short-range ordering are largely enhanced, whereas the bond pairs being related to fcc and hcp crystalline order increase at first then decrease. The pressure effect on various bond pairs for liquids is larger than for glasses. Two kinds of bond pairs, which exist in large proportion in the amorphous, are demonstrated for the transformation from 1431 to 1541 bond pairs when decreasing temperature or increasing pressure below glass transformation temperature (Tg). Although the sum of these two pairs keeps unchanged below Tg, the role of them is like a bridge which links another two different kinds of bonded pairs, icosahedral ordering and crystalline ordering pairs.