Glass formability and the Al–Au system

Abstract

The aluminum–gold system exhibits various features that suggest high glass formability, such as a deep eutectic, formation of icosahedral clusters in the intermetallic compound near the eutectic minimum and a strongly negative heat of mixing. However, it is very difficult to form a glass with this system. Various issues related to glass formability are discussed using the Al–Au system as a negative test-case. In particular, the atomic level pressure was calculated from first principles for the first time for Al2Au, AlAu2 and AlAu4 intermetallic compounds. The atomic level pressure is very high in these compounds, suggesting frustrated electronic states which destabilize both crystalline and glassy phases.