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, Ca 50Mg20Cu30, and Ca55Mg 18Zn11Cu16, 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 Ca 55Mg18Zn11C16 BMG possessed the most favorable oxidation resistance, followed closely by the Ca50Mg 20Cu30 BMG, with the Ca65Mg15Zn 20 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. © 2007 The Japan Institute of Metals.