Effect of Al on the atomic structure in Zr50Cu40Al10 metallic glass

The icosahedral short-range order and medium-range order of Zr50Cu50 and Zr50Cu40Al10 metallic glasses have been investigated by molecular dynamics simulations. Our analysis shows that, although the replacement of a few percent of Cu by Al enlarges the population of full icosahedra (FIs), the degree of interpenetrating aggregation for FIs is reduced which might be caused by the strong avoidance of Al-centered FIs in the ternary system. However, this fact does not mean the weakness of icosahedral medium range order in Zr50Cu40Al10 metallic glass. If the interpenetrating and non-interpenetrating connections are both considered, the largest super-cluster formed by the connected FIs in Zr50Cu40Al10 is rather larger than that in Zr50Cu50, which might play an important role in slowing down the kinetics and thus enlarge the glass-forming ability. (C) 2016 Elsevier B. V. All rights reserved.