Influence of Grain Shape, Size, and Grain Boundary Diffusion on High-Temperature Oxidation of Pure Metal Fe, Cu, and Zn

Influence of grain shape, size, and grain boundary diffusion on high-temperature oxidation of pure metals such as Fe, Cu, and Zn was investigated in this article. The oxidized scale was developed on the outer layer of the metal surface depending on the geometrical parameter of the metal-scale system as well as diffusion direction through boundary layers towards the base of the material. The creation of the inner layer and the morphological structure developed from the internal stress generated during the growth of the oxide scale and by diffusion of metal/air system. The oxidation rate depends on the cation and anion mobile transport of the metal in the inward and outward direction of the diffusion layer. Oxidation rate was decreased with the decreasing grain size of the pure metal, whereas Zn metal deviated from this principle. A strong correlation between rate of oxidation and grain shape, size was established.