ABSTRACT
Acknowledgments .........................................................................................................................141
References .....................................................................................................................................141
As a new structural material, amorphous metals require more effort and improvement in the area of
damage tolerance; however, there are many impressive properties with respect to strength, cor-
rosion resistance, elastic limits, etc., (Table 6.1, Figure 6.1). Pursuing improvements in ductility is
ongoing. When the specific properties are considered, these alloys are further set apart from their
crystalline counterparts. Most metallurgical materials usually contain crystalline structures not far
from thermodynamic equilibrium. Metallic glasses with amorphous structures similar to the liquid
solutions but at temperatures well below the melting points can be synthesized using controlled
solidification techniques with sufficient cooling rates to avoid crystallization of at all phases. Over
the past few years, extensive worldwide exploration has led to discoveries of new families of
metallic glass systems including Zr-, Fe-, Mg-, Cu-, Ca-, Ce(Nd)–, Ti-, Y-, and Ni-, etc.
Details of some of these successes are available from the most recent reviews by Inoue [1],
Poon et al. [2], and Wang et al. [3]. Various strategies are employed and a number of empirical
rules have been inferred. However, in the case of rapid solidification, the competing phase transfor-
mation kinetics determines the final product. The controlling factors are principally the atomic
mobility and thermodynamic properties of each potential phase, which varies with composition and
temperature. The glass forming ability (GFA) of metallic alloys will be analyzed in this chapter
with particular attention given to the thermodynamic perspective. Because bulk amorphous metal
alloys are now routinely produced, their amorphous, partially crystalline and fully crystalline forms
yield new advanced structural alloys. Even in a fully crystalline form, structures and properties can
now be obtained with the new thermodynamic and kinetic pathways available from an amorphous
precursor that previously could not be attained by any other route. This article will examine some of
the thermodynamics and kinetics associated with obtaining these pathways.
