Chemical ordering around open-volume regions in bulk metallic glass Zr52.5Ti5Al10Cu17.9Ni14.6

Abstract

We provide direct experimental evidence for a nonrandom distribution of atomic constituents in Zr52.5Ti5Al10Cu17.9Ni14.6 bulk metallic glass using positron annihilation spectroscopy. The Ti content around the open-volume regions is significantly enhanced at the expense of Ni and Cu. Our results indicate that Ni and Cu atoms closely occupy the volume bounded by their neighboring atoms while Al, Ti, and Zr are less closely packed, and more likely to be associated with the open-volume regions. The overall distribution of elements seen by the positron is not significantly altered by annealing or by crystallization. Theoretical calculations indicate that the observed elemental distribution is not consistent with the known crystalline phases Zr2Cu and NiZr2, while Al3Zr4 shows some of the characteristics seen in the experiment.