EFFECTS OF RARE EARTHS AND REACTIVE ELEMENTS ON THE OXIDATION RESISTANCE OF Ni-20Cr ALLOY.

Abstract

The isothermal oxidation behavior of Ni-20Cr alloys with 0. 7 mass% of reactive elements (Y, La, Al, Zr, Ti and Si) was investigated in air at 1273 and 1373 K. The alloying elements except for Ti reduced the oxidation rate at 1273 and 1373 K. The highest oxidation resistance was obtained by a Ni-20Cr-0. 7Y alloy at a lower temperature (1273 K) and during the early stage of oxidation at a higher temperature (1373 K). A Ni-20Cr-0. 7Al alloy showed the highest oxidation resistance after 72 ks at 1373 K with the formation of the internal oxide layer alpha -Al//2O//3. The addition of 0. 7%Ti reduced oxidation resistance of the Ni-20Cr alloy.