In this study, the room-temperature oxidation behaviors of three Ca-based bulk amorphous alloys, Ca 65 Mg 15 Zn 20 , Ca 50 Mg 20 Cu 30 , and Ca 55 Mg 18 Zn 11 Cu 16 , 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 55 Mg 18 Zn 11 Cu 16 BMG possessed the most favorable oxidation resistance, followed closely by the Ca 50 Mg 20 Cu 30 BMG, with the Ca 65 Mg 15 Zn 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.
The use of X-ray residual stress determination as a technique for evaluating the damage incurred by nickel-based, Cr 2 O 3 -forming superalloy materials under various service conditions (isothermal heating, thermal cycling, applied stress, stressed and cycled) was investigated. Large and small compressive residual stresses were observed for the oxides and the near surface substrates, respectively. It was expected that the applied stresses and thermal cycling would cause an enhanced degree of oxidation damage that would translate into appreciable differences in residual stress values. Differences in the magnitude of residual stress values were not appreciable condition-to-condition, however. An increase in the severity of the oxidizing conditions in the form of longer oxidation times, higher oxidizing temperatures, and a much greater frequency of thermal cycling is suggested for future studies.
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