Dispersed phases in powder metallurgically-produced alloys: contributions to high-temperature oxidation behavior

Microstructural Impacts on the Oxidation of Multi-Principal Element Alloys

“…Apart from the 1000°C annealed, nonisothermal-isothermal series, materials that contained smaller precipitates outperformed their larger precipitate counterparts in terms of overall mass gain for both oxidation tests. This effect seems to stem from the coalescence of internal Al 2 O 3 that is forming beneath the Cr 2 O 3 layer as oxidation progresses which may act to block further oxide development [30,34]. If the initial Ni 3 (Al,Ti) precipitate distribution is taken to be the nucleation sites for Al 2 O 3 growth, their growth rate, , should follow classical Lifshitz-Slyozov-Wagner coarsening and is therefore proportional to [66].…”

“…A preliminary model to characterize a secondary phase's ability to maintain an oxide scale was devised in terms of precipitate chemistry and volume fraction [29]. While this relationship is more of a modi cation to the original Wagner criteria, it has proven to be a reasonable predictor of oxide products for concentrated alloys containing multiple phases [30,34]. To delve further into the kinetic basis for the reservoir effect, the diffusion columns above the secondary phases were considered [35].…”