Short-range order of Zr62-xTixAl10Cu20Ni8 bulk metallic glasses

The short-range order and crystallization behavior of slowly cooled Zr62-xTixAl10Cu20Ni8 bulk metallic glasses have been investigated in terms of the atomic pair correlation function as a function of Ti content x (2less than or equal toxless than or equal to7.5). The structural parameters point to the presence of chemical short-range order in these bulk glasses. An enhanced local excess free volume around the Ti atoms is concluded from density measurements. The first stage of crystallization in Zr62-xTixAl10Cu20Ni8 bulk glasses is related to changes in the medium-range order while the first neighborhood is retained. The atomic pair correlation functions of the first crystallization products are similar for all titanium contents. There is no indication of any special atomic arrangement for the particular alloy forming quasicrystals upon heating (x=3). In case of Zr54.5Ti7.5Al10Cu20Ni8 an ultrafine microstructure consisting of clusters of 2 nm in size is formed as the first step of crystallization. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.