Effect of lanthanum on oxidation behavior of Ni-20Cr- 18W-1Mo alloys at 1373 K for 100 h in air

The isothermal oxidation experiments of Ni-20Cr-18W-1Mo superalloys with and without lanthanum element were conducted at 1373 K for 100 h in air. The oxide scales surface and the cross-section of isothermal oxidation samples were analyzed by scanning electron microscope, energy-dispersive X-ray spectroscopy and X-ray diffraction. Results show that the addition of La can significantly improve the binding ability between the matrix and the oxide scales, and consequently the oxidation resistance of Ni-20Cr-18W-1Mo alloy at 1373 K is improved. Comparing with that without La, the Ni-20Cr-18W-1Mo alloy with La has smaller parabolic rate constant κ" and weaker spalling oxidation, and the surface of oxide scales are much more compact.