Role of Hf4+ Doping on Oxygen Grain Boundary Diffusion in Alumina.

摘要

The growth of protective alumina scales in Al2O3-forming alloys can be affected by the addition of reactive elements, such as Hf(4+), which has been considered one of the most effective dopants to slow down the scale growth rate. While a number of theories concerning the "reactive element effect" have been proposed, a full explanation of this phenomenon is not yet available. The overall objective for this study was to conduct a systematic series of model experiments in order to elucidate the effect of HfO2 on oxygen grain boundary transport in alumina. The key questions to focus in the current work are: How do the doping levels of HfO2 / oxidizing temperature affect oxygen grain boundary diffusion in alumina? First part of this work investigated the effect of doping levels of HfO2 on oxygen grain boundary transport in alumina, which contains uniformly distributed Ni metallic particles. The second part of the work is focused on the temperature dependence of the oxidation kinetics in HfO2 doped AI2O3.