Oxidation behavior of Ni-based superalloy GH738 in static air between 800 and 1000℃
来源期刊：Rare Metals2021年第3期
论文作者：Jue Wang Hao Xue Ying Wang
文章页码：616 - 625
摘 要：The oxidation behavior of a nickel-based superalloy GH738 was studied by isothermal oxidation tests in still air at different temperatures,with exposure time up to 100 h.Oxidation-kinetic curves were plotted using the mass gain method.The surface and cross-sectional morphologies were observed by scanning electron microscopy（SEM）.A composition analysis and an oxidation-product identification were conducted using energydispersive X-ray spectroscopy（EDS） and an X-ray diffraction（XRD）,respectively.The results showed that GH738 exhibited parabolic oxidation-kinetic curves,with stable parabolic-rate constants at each temperatures.The activation energy of oxide growth was calculated to be329.6 kJ·mol-1.Cr2 O3（chromia） was the external oxidation product at 800℃.A TiO2-Cr2 O3 double-layer structure was formed at 900℃.The position of TiO2 changed from the oxide-metal interface to the air-oxide interface by the diffusion of Ti atoms in chromia during the oxidation time at this temperature.Spallation was observed in the Cr0.12Ti0.78O1.74-Cr2 O3 multi-layer oxide of at1000℃,which increased the oxidation rate.For all the tests,the main internal oxide was always Al2 O3.The entire GH738 oxidation process was interpreted by the competitive diffusion of elements（Cr,Ti,Ni,etc.） in metal matrix and chromia,while a schematic diagram of oxidation process was proposed.
Jue Wang1,2，Hao Xue2，Ying Wang2
1. Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology2. School of Materials Science and Engineering,Nanjing Institute of Technology
摘 要：The oxidation behavior of a nickel-based superalloy GH738 was studied by isothermal oxidation tests in still air at different temperatures,with exposure time up to 100 h.Oxidation-kinetic curves were plotted using the mass gain method.The surface and cross-sectional morphologies were observed by scanning electron microscopy（SEM）.A composition analysis and an oxidation-product identification were conducted using energydispersive X-ray spectroscopy（EDS） and an X-ray diffraction（XRD）,respectively.The results showed that GH738 exhibited parabolic oxidation-kinetic curves,with stable parabolic-rate constants at each temperatures.The activation energy of oxide growth was calculated to be329.6 kJ·mol-1.Cr2 O3（chromia） was the external oxidation product at 800℃.A TiO2-Cr2 O3 double-layer structure was formed at 900℃.The position of TiO2 changed from the oxide-metal interface to the air-oxide interface by the diffusion of Ti atoms in chromia during the oxidation time at this temperature.Spallation was observed in the Cr0.12Ti0.78O1.74-Cr2 O3 multi-layer oxide of at1000℃,which increased the oxidation rate.For all the tests,the main internal oxide was always Al2 O3.The entire GH738 oxidation process was interpreted by the competitive diffusion of elements（Cr,Ti,Ni,etc.） in metal matrix and chromia,while a schematic diagram of oxidation process was proposed.
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