ZrN Phase Formation, Hardening and Nitrogen Diffusion Kinetics in Plasma Nitrided Zircaloy-4. Academic Article uri icon

abstract

  • Plasma nitridation was conducted to modify the surfaces of Zircaloy-4. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman analysis were used to characterize microstructures and phases. Surface indentation and cross-sectional indentation were performed to evaluate mechanical property changes. Nitridation forms a thin layer of ZrN phase, followed by a much deeper layer affected by nitrogen diffusion. The ZrN phase is confirmed by both TEM and Raman characterization. The Raman peaks of ZrN phase show a temperature dependence. The intensity increases with increasing nitridation temperatures, reaches a maximum at 700 C, and then decreases at higher temperatures. The ZrN layer appears as continuous small columnar grains. The surface polycrystalline ZrN phase is harder than the bulk by a factor of ~8, and the nitrogen diffusion layer is harder by a factor of ~2-5. The activation energy of nitrogen diffusion was measured to be 2.88 eV. The thickness of the nitrogen-hardened layer is controllable by changing the nitridation temperature and duration.

published proceedings

  • Materials (Basel)

author list (cited authors)

  • Balerio, R., Kim, H., Morell-Pacheco, A., Hawkins, L., Shiau, C., & Shao, L.

citation count

  • 0

complete list of authors

  • Balerio, Robert||Kim, Hyosim||Morell-Pacheco, Andres||Hawkins, Laura||Shiau, Ching-Heng||Shao, Lin

publication date

  • June 2021

publisher