Molecular dynamics study of structural formation in Cu50–Zr50 bulk metallic glass

• Formation pathway of full icosahedra in Cu50–Zr50 BMG at 300 K was back-traced.
• (0,2,8,2), (0,1,10,2) and (1,0,9,3) polyhedra have high tendency to convert into full icosahedra.
• Thermal stability of icosahedra and their connections emerges at glass transition temperature.
• Formation of IS-linked chains in the glass during cooling was studied.

In this work, the evolution of the local structure in Cu50–Zr50 bulk metallic glass during glass formation was studied by molecular dynamics simulation. The pair distribution function and Voronoi analysis were adopted to characterize local structures in this alloy. The stability of icosahedral clusters and the role of other local clusters in the formation of icosahedra were evaluated. It was found that the (0,2,8,2) polyhedron is not only the dominant cluster in this alloy, but also the most prone cluster to convert into an icosahedron in the course of cooling. Moreover, it acts as an intermediate state during the icosahedron formation. The onset of stability of icosahedra emerges at the glass transition temperature and increases by decreasing temperature. It was also found that the intercross connection between icosahedra is the most stable type of connection between icosahedra. Besides, the stability of vertex sharing, edge sharing and face sharing between icosahedrons is almost the same.