Study on Si-like and topologically close-packed structures during rapid solidification of Au-Si alloys

Abstract

A molecular dynamics (MD) simulation has been conducted to investigate the Si-like and topologically close-packed (TCP) structures in AuxSi(100−x) alloys during rapid solidification at the cooling rate of 1 × 1011 K/s. A new method named largest standard cluster analysis (LSCA) is performed to analyze and characterize the microstructural evolution during solidification. Results indicate that it is difficult to crystallize for each kind of Au-Si alloy, but eventually freeze into amorphous solids. The Si-like structures with low coordination number are significantly formed in the Si-rich alloys with Au content CAu≤30%, while TCP structures with higher packing density prefer to form in the Au-rich alloys with CAu≥80%. Moreover, the Si-like Medium-range order (MRO) structures are more likely to link with each other by 1100 bond-type, while the more denser TCP MROs are inclined to combine by 1551 bond-type. This provides new analysis ideas and methods for studying the amorphous structure between transition metal and semiconductor.