Isothermal oxidation behavior of cast Ni-base superalloy K44
(1.辽宁省沈阳市沈阳化工学院应用化学系
2.College of Applied Chemistry, Shenyang Institute of Chemical Technology, Shenyang 110142, China
3.Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
4.Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016, China
5.School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China)
2.College of Applied Chemistry, Shenyang Institute of Chemical Technology, Shenyang 110142, China
3.Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
4.Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016, China
5.School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China)
Abstract: The oxidation behavior of a cast Ni-base superalloy K44 in air at 850？1 000 ℃ for l00 h was studied. The scales on the surface were determined by SEM and EPMA equipped with an EDXS. The results show that oxidation kinetics obey the parabolic law from which the values of activation energy Qp1=221.1 kJ/mol and Qp2=247.6 kJ/mol are estimated. The oxidation scales are composed of loose outer layer of TiO2/TiO-Cr2O3 and a small amount of NiCr2O4 and NiA12O4, compact intermediate layer Cr2O3, and precipitate of internal oxides A12O3.
Key words: K44 superalloy; high temperature oxidation; oxidation kinetics