The surface structure of gas-atomized metallic glass powders

By means of X-ray photoelectron spectrometry depth profile and transmission electron microscopy analysis, this study reveals that amorphous Cu(54)Ni(6)Zr(22)Ti(18) powders are enveloped by a thick (similar to 30 nm) oxide skin and a subsequent oxidation-induced partially nanocrystallized zone. The thick oxide skin changes the metallic glass surface to oxide ceramic. It is proposed that effective disruption of the oxide skin is essential to the sintering of metallic glass.