Bulk Metallic Glasses (BMGs): Glass Formation and Alloy Design
C. T. Liu and Z. P. Lu
Metals and Ceramics Division
Oak Ridge National Laboratory
Oak Ridge, TN 37831
Bulk Metallic Glasses (BMGs) constitute a new class of metallic materials that possess
attractive physical and mechanical properties for structural and functional use. In the
study of BMGs, it is vitally important for us to understand the nature of glass formation,
to predict glass-forming ability (GFA), and to design new bulk metallic glasses with
superior GFA. For the past four decades, only limited progress had been made in
analyzing the glass formation in various glass forming systems. Glass formation always
involves a competing process between liquid phases and resulting crystalline phases.
Based on the consideration of both liquid phase stability and resistance to crystallization,
we have recently developed a new expression,  = Tx/(Tg + Tl), to measure the GFA of
BMGs, where Tx is the onset temperature of crystallization, Tg the glass transition
temperature, and Tl the liquidus temperature. Experimental data in the literature strongly
support that  is effective in predicting the GFA of various glass-forming systems. In
order to design BMGs with superior GFA, it is necessary for us to increase liquid phase
stability and suppress crystalline phase formation. Recently, we have successfully
designed Fe-based BMGs with superior glass forming ability by alloying with minor
amounts of yttrium additions in existing metallic glass materials This research was
sponsored by the Division of Materials Sciences and Engineering, Office of Basic Energy
Sciences, US Department of Energy under contract DE-AC05-00OR-22725 with UTBattelle, LLC.