A deep eutectic point in quaternary Zr–Ti–Ni–Cu system and bulk metallic glass formation near the eutectic point

Zr-rich Zr–Ti–Ni(Cu) alloy system with deep eutectics was investigated for bulk metallic glass (BMG) compositions. The BMGs were investigated by locating deep eutectic compositions and by evaluation of alloys near it. When Cu was added to the Zr45Ti21Ni34 eutectic alloy as an additional melting point depressant, even lower melting eutectics were obtained. A new quaternary eutectic alloy was found with a composition of Zr49Ti17Ni20Cu14. The microstructure consists of three glass forming compounds of Zr2Ni, Zr2Cu, and (Zr,Ti)2Ni. By examining alloys around the new quaternary eutectic alloy, a BMG with a glass forming ability of 4 mm diameter was found at the off-eutectic Zr49Ti14Ni20Cu17 composition. The study confirmed the composition of the best glass former near the eutectic point. The searching method for BMGs starting from a deep eutectic alloy as a reference point is described.