Glass Forming Ability and Crystallization Kinetics of Cu-Zr-Al-(Y, Ag) Amorphous Alloy

Abstract

Cu-Zr-Al-(Y, Ag) amorphous alloy ribbons of Cu₅₀Zr₄₂A_l8, Cu₄₆Zr_47-xAl₇Y _x(x=2, 5), Cu₄₃Zr₄₂Al₈Ag₇, and Cu₄₃Zr₄₂Al₈Ag₅Y₂ were prepared using the single roller melt-spinning method. The glass forming ability and non-isothermal crystallization behavior of the amorphous alloys were investigated by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) in a continuous heating mode. The experimental results show that the glass forming ability and thermal stability of Cu-Zr-Al amorphous alloys are improved by adding minor amounts of Y and Ag, and the effect of Ag on the glass forming ability is more significant than that of Y. Compared to the Cu₅₀Zr₄₂A_l8 alloy, the width of the supercooled liquid region of the Cu₄₆Zr_47-xAl₇Y _x(x = 2 and 5) alloys increased by 19 K and 30 K, respectively. The reduced glass transition temperature (T _rg) and the parameter γ of the two alloys enhanced separately. Compared to the Cu₅₀Zr₄₂A_l8 alloy, the T _rg and γ values of both Cu₄₃Zr₄₂Al₈Ag₇ and Cu₄₃Zr₄₂Al₈Ag₅Y₂ alloys enhanced noticeably up to 0.619, 0.417, and 0.609, 0.412, respectively. The crystallization activation energies of the amorphous alloys calculated by the Kissinger and Flynn Wall Ozawa equations increased with the addition of minor Y and Ag into the Cu₅₀Zr₄₂A_l8 alloy. The addition of Y and Ag significantly improved the thermal stability of the Cu₅₀Zr₄₂A_l8 amorphous alloy.

Keywords

amorphous alloy / yttrium / micro-alloying / non-isothermal crystallization