Crystallization behaviors of the bulk amorphous alloy Ni ₆₀Zr₂₅Al₈Y₇

The effects of partial replacements of Zr by Y in the alloy Ni ₆₀Zr_25-xAl₈Y₇ and 7 at %) on the crystallization behaviors of amorphous alloys were studied using isothermally heat-treated ribbons. With the partial replacement, the supercooled liquid region upon continuous heating was significantly extended indicating that crystallization can be effectively suppressed by the optimum amount of Zr replacement by Y. The first phase appeared during crystallization was identified as the ternary compound AlNi₂Zr while the single exothermic event could be observed upon heating the amorphous ribbons. The AlNi₂Zr phase was decomposed into binary compounds upon further heating. Therefore, the extended supercooled liquid region of the alloy Ni₆₀Zr ₂₅Al₈Y₇ was attributed to the suppression of AlNi₂Zr phase formation by the partial replacement of Zr by Y. The effects of Y on the crystallization behaviors were discussed on the basis of atomic configuration of the supercooled liquid.