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Keywords:

  • directional solidification;
  • eutectic alloys;
  • oxidation;
  • surface analysis;
  • thermal stability

Abstract

Oxidation behavior and thermal stability of a NiAl–V alloy with eutectic composition processed by directional solidification technique has been investigated. The surface analysis at the elevated temperature indicated that the investigated microstructures are stable at the isothermal conditions and an inert atmosphere. The oxidation testing in the synthetic air showed that the temperature of 400 °C is critical. In addition, the oxidation of the NiAl–V eutectic alloy is characterized by: (a) alteration of composition immediately below the surface substrate/oxide; (b) formation of the oxide layer rich in V, adherent to the substrate; and (c) formation of external oxide layer that presents oxide mixture formed by vanadium, nickel, and aluminum. pssa201200836-gra-0001

Microstructure of the substrate/oxide interface of NiAl–V alloy oxidized at 900 °C for 24 h.