Bulk Metallic Glass Formation near a Quaternary Cu-Zr-Ti-Al Eutectic Point

Abstract

The glass-forming ability (GFA) of the CuZr-based alloys with addition of equivalent atomic ratio of Ti and Al is investigated. We show that the addition of Ti and Al is effective to increase the GFA of the binary Cu₅₀Zr₅₀ alloy. As the content of Ti and Al increases from 0 to 10 at%, the GFA of the quaternary Cu-Zr-based alloys increases. The critical diameter of the Cu₄₆Zr₄₆Ti₄Al₄ and Cu₄₅Zr₄₅Ti₅Al₅ alloys is up to 6 mm. Moreover, we found that the critical diameter of a glassy rod is 7 mm for the Cu_45.5Zr_45.5Ti_4.5Al_4.5 alloy. The compositions of these alloys with high GFA are closer to a CuZrTiAl quaternary eutectic. However, much higher contents of Ti and Al lead to the precipitation of the simple TiAl phase, which degrades the GFA of the alloys.