Oxidation mechanisms of β-NiAl + Zr determined by SIMS

Abstract The oxidation mechanisms of single crystal Zr-doped β-NiAl from 800 to 1200 °C were determined using primarily secondary ion mass spectrometry (SIMS) imaging and depth profiling. High spatial resolution SIMS imaging provides a means for critically assessing the effects of diffusion through the boundaries of the various morphologies of α-Al 2 O 3 scales that form on β-NiAl. Transient oxidation occurs by outward Al diffusion through transition Al 2 O 3 scales, θ-Al 2 O 3 in this case, for temperatures from 800 to 1100 °C. Steady-state oxidation occurs by counter-diffusion of oxygen inward and both Al and Zr outward through boundaries in the α-Al 2 O 3 ridge morphology.