Bulky amorphous alloys in a cylindrical shape with diameters up to 16 mm were found to form by water quenching a Zr65Al7.5Ni10Cu17.5 melt in a quartz tube. The amorphous phase of this alloy has the widest temperature interval of supercooled liquid region before crystallization. The glass transition temperature, crystallization temperature and Vickers hardness for the bulky amorphous alloy with a diameter of 16 mm are 625 K, 750 K and 465, respectively, being nearly the same as those for the corresponding melt-spun ribbon with a thickness of 30 μm. The extremely large glass-forming ability is presumably due to a combination of significantly different atomic size ratios among the constituent elements and the necessity of redistribution of Al for the progress of crystallization. The finding of the extremely large glass-forming ability has a very important implication because it demonstrates the possibility of bulk amorphous alloy production by conventional casting processes.
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