Formation of a Ni- and Be-free Zr-based glassy alloy in centimeter scale

Abstract

A Ni- and Be- free Zr-Al-Cu-Y glassy alloy in centimeter scale has been developed and understood via clusters in this letter. Glass-formers in Zr-Al-Cu system was understood and constructed by Zr-Al and Zr-Cu clusters proportionately. Clusters Cu-Cu7Zr5 and Al-Al2Zr8, which conform to the topological packing compact criterion, were chosen and used. The ratio between clusters is determined by electrons per atom ratio. Alloy with highest GFA located at Zr48.65Cu43.24Al8.11 which could be regarded as 0.5Al-Al2Zr8 + Cu-Cu7Zr5. Its critical diameter is 6 mm, superior than Zr50Cu40Al10 of which critical diameter is about 3 mm at the same laboratory environment. Furthermore, 2 at.% Y alloying greatly enhances GFA leading to centimeter scale. Its reason was also discussed from the aspect of clusters. The results in this letter might provide a way of designing good glass-formers, understanding microalloying and expand the application range of amorphous alloys.