Co-Al-W-0.1B superalloys have been isothermally oxidized at 900℃ for 1000,5000 and 10000 h in order to investigate their oxidation behaviors.The oxide layers and morphologies were characterized by X-ray diffraction a...Co-Al-W-0.1B superalloys have been isothermally oxidized at 900℃ for 1000,5000 and 10000 h in order to investigate their oxidation behaviors.The oxide layers and morphologies were characterized by X-ray diffraction and scanning electron microscopy combined with energy-dispersive spectroscopy.After1000 h exposure,a Co3W/γ zone,an Al2O3layer,a mixture of Co,Al,W oxides layer and a CoO layer are established on the substrate alloys.After extended oxidation,a discontinuous Al2O3layer in Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys leads to an additional mixed oxide layer on the substrate instead of the Co3W/γ zone.The oxide layers that form on the Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys are much thicker than those on the Co-9Al-11W-0.1B alloy,and continuously thicken during oxidation.The higher content of W is beneficial to improving the oxidation resistance as it facilitates a faster formation of Co3Was well as Al2O3.展开更多
基金funding from the China Scholarship Council program(No.201306290056)supported by the National Natural Science Foundation of China(No.51775440)
文摘Co-Al-W-0.1B superalloys have been isothermally oxidized at 900℃ for 1000,5000 and 10000 h in order to investigate their oxidation behaviors.The oxide layers and morphologies were characterized by X-ray diffraction and scanning electron microscopy combined with energy-dispersive spectroscopy.After1000 h exposure,a Co3W/γ zone,an Al2O3layer,a mixture of Co,Al,W oxides layer and a CoO layer are established on the substrate alloys.After extended oxidation,a discontinuous Al2O3layer in Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys leads to an additional mixed oxide layer on the substrate instead of the Co3W/γ zone.The oxide layers that form on the Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys are much thicker than those on the Co-9Al-11W-0.1B alloy,and continuously thicken during oxidation.The higher content of W is beneficial to improving the oxidation resistance as it facilitates a faster formation of Co3Was well as Al2O3.
