The oxidation behavior of Cu42Zr42Al8Ag8 bulk metallic glasses

The oxidation behavior of Cu 42 Zr 42 Al 8 Ag 8 bulk metallic glass was studied in synthetic air over the temperature range of 330–460 °C. The oxidation kinetics of the metallic glass follows a single parabolic rate law at 330 and 390 °C and a two-stage parabolic rate law from 420 to 460 °C. Silver precipitates on the topmost oxide layer of the metallic glass were revealed by energy-dispersive X-ray spectroscopy together with X-ray diffraction pattern. Observation using scanning electron microscopy shows that silver metal precipitated at all temperatures and some islands were formed on the outermost copper oxide layer at high temperatures. Multilayered oxide scales were also observed with silver precipitates sandwiched between copper- and zirconium-rich oxides layers.