High-Temperature Oxide Regrowth on Mechanically-Damaged Surfaces...

Here we report the effects of mechanical damage from a sharp stylus on the regrowth of oxide layers on a Ni-based superalloy known as Pyromet 80A�. It was found that the oxide that reformed on the damaged portion of a pre-oxidized surface differed from that which formed on undamaged areas after the equal exposures to elevated temperature in air. These findings have broad implications for modeling the processes of material degradation in applications such as exhaust valves in internal combustion engines because they imply that static oxidation data for candidate materials may not adequately reflect their reaction to operating environments that involve both mechanical contact and oxidation.