Correlation between Glass Formation and Type of Eutectic Coupled Zone in Eutectic Alloys

Glass formation is basically to avoid nucleation upon quenching. However, the growth of each nucleus is also important as certain undercooling is needed. Thus the subsequent competition between the growth of crystalline phases and the formation of amorphous phase should be considered. In this paper, we summarized our recent studies in Pd-Ni-Cu-P system and La-Cu-Ni-Al alloy systems. It is concluded that the glass forming ability of a eutectic alloy system depends on the type of the eutectics, i.e. symmetric or asymmetric eutectic coupled zone. For the alloy systems with symmetric eutectic coupled zone, the best glass forming alloys should be at or very close to the eutectic composition. For the alloys with asymmetric eutectic coupled zone, the best glass forming alloys should be at off-eutectic compositions.