The Oxidation Behaviour Of The Pulse Plasma Sintered -Nial Intermetallic Compound Under Thermal Cycling Conditions At 1150 Degrees C

The effect of microstructure engineering using a new manufacturing route (pulse plasma sintering (PPS)) on the high temperature oxidation behaviour of -NiAl coating material with and without small amounts of Hf was determined at 1150 degrees C under thermal cycling conditions in air. Vacuum melted -NiAl compounds with and without Hf were used as reference materials and tested under the same conditions. The oxide scales were observed using SEM and analysed using EDX. The results showed that the Hf-containing materials behaved better than Hf-free ones and among the Hf-containing materials, the vacuum melted one exhibited significantly better cyclic oxidation resistance than the PPS material. Thus, no improvement of the oxidation resistance was achieved using the applied manufacturing procedure. The scales prone to spallation were at considerably later stages of the scale evolution and less intact with the substrate than the scale resistant to spallation.