Oxidation Behavior of Ca-Based Bulk Amorphous Materials

Abstract

In this study, the room-temperature oxidation behaviors of three Ca-based bulk amorphous alloys, Ca₆₅Mg₁₅Zn₂₀, Ca₅₀Mg₂₀Cu₃₀, and Ca₅₅Mg₁₈Zn₁₁Cu₁₆, were examined under normal flowing laboratory air and compared with the oxidation behaviors of these alloys in the crystalline form under identical conditions. The degree of oxidation for alloys in the amorphous and crystalline conditions was investigated by periodically measuring the mass change over the oxidation time. From the results of the oxidation mass change, and oxide thickness measurements obtained from scanning-electron-microscopy (SEM) studies, it was determined that the Ca₅₅Mg₁₈Zn₁₁Cu₁₆ BMG possessed the most favorable oxidation resistance, followed closely by the Ca₅₀Mg₂₀Cu₃₀ BMG, with the Ca₆₅Mg₁₅Zn₂₀ BMG having the least favorable oxidation resistance. The trend in glass-forming abilities of the three compositions follows the same trend as the oxidation resistance in the three alloys. In all cases, the oxidation resistance of the amorphous alloys was superior to the oxidation resistance of the same alloys in the crystalline state.