On the heredity and evolution of icosahedral clusters during the rapid solidification of liquid Cu50Zr50 alloys

A molecular dynamics simulation is performed to investigate the heredity characteristics of icosahedral clusters during the rapid solidification of liquid Cu50Zr50 alloy at a cooling rate of 5K/ns. The analysis from a cluster-type index based on the H–A bond-type index shows that (12 0 12 0) icosahedra and their distorted configurations (12 8/1551 2/1541 2/1431) play a key role in the formation of glassy alloys. At Tg, the numbers of (12 0 12 0) and (12 8/1551 2/1541 2/1431) basic clusters significantly increase and most of which are Cu-centered Cu6Zr7, Cu7Zr6 and Cu5Zr8 clusters. An inverse tracking investigation on the configuration evolution during the rapid solidification further reveals that the configuration heredity of icosahedral clusters in the super-cooled liquid is an intrinsic feature of the rapidly solidified Cu50Zr50 alloys, but the onset of configuration heredity merely emerges in the super-cooled liquid region of Tm–Tg. Below Tg, the perfect heredity of icosahedra is dominant and a distinctly ascent in heredity fraction fi takes place at Tg. Relative to (12 8/1551 2/1541 2/1431) distorted icosahedra, the standard (12 0 12 0) icosahedra are of high structural stability and large genetic ability, and most of which are passed down by means of the configuration rather than the chemical order. •Evolution of atomic configurations is tracked inversely.•Heredity of icosahedra is an intrinsic feature of rapidly solidified alloys.•Onset states of heredity emerge in supercooled liquid regions of Tm–Tg.•Standard icosahedra have stronger genetic ability than distorted icosahedra.•Direct and perfect heredity of icosahedra is dominant below Tg.