Microstructure Evolution of Ni-Co Alloys During Crystallization and Amorphization Process.

A molecular dynamics simulation has been conducted in Ni73Co27 and Ni74Co26 alloys during rapid solidification at the cooling rate of 1 × 1012 K/s. It indicates that two phase transitions occur with twice drops, and the number of FCC increases suddenly in Ni73Co27 alloy. And finally, FCC atoms are dominant with the amount of 92.94% at 300 K, which neatly arranges themselves into the crystalline structure. A lot of topologically close-packed clusters are formed in Ni74Co26 alloy, indicating the formation of metallic glass. The differences between the formations in crystalline hexagon and amorphous pentagon are demonstrated by three-dimensional visualization. [ABSTRACT FROM AUTHOR]