Cyclic oxidation of beta-NiAl with various reactive element dopants at 1200 degrees C

Cyclic oxidation of beta-NiAl alloys doped with different reactive elements (REs) each of which had an optimized concentration was investigated. All of REs effectively suppressed growth of voids beneath oxide scales formed on the alloys. The La-doped alloy suffered from severe internal oxidation. The Hf or Zr-doped alloys exhibited lower oxidation rate, while the Dy-doped alloy showed less scale rumpling. The effect mechanisms associated with solid solubility and ion size of RE dopants on cyclic oxidation were discussed. Co-doping of REs, such as Dy and Hf or Zr, could be anticipated to provide better cyclic oxidation performance. (c) 2012 Elsevier Ltd. All rights reserved.