Atomic packing in Mg(61)Cu(28)Gd(11) bulk metallic glass

Atomic configurations of an Mg(61)Cu(28)Gd(11) bulk metallic glass and its molten state have been investigated. The supercooled liquid and melt have a volume expansion coefficient only two times as large as that below glass transition temperature. Although the dominant polyhedra are 12- and 13-coordinated, the melt has slightly more polyhedra of low coordinated and less of high coordinated than in the as-cast. By Gd addition, half-octahedra with more volume accommodated are likely formed in the polyhedra, causing the local atomic environments of Mg in the melt quite different from the competing crystalline phase, thereby suppressing crystallization upon quenching. (C) 2011 American Institute of Physics. [doi:10.1063/1.3544049]