Effect of columnar nano-grain structure on the oxidation behavior of low-Cr Fe-Co-Ni base alloy in air at 800 ℃

摘要

The nanocrystalline coating of a low-Cr Fe-Co-Ni base alloy with 0.36 wt.% Si was deposited on the as-cast low-Cr alloy with identical compositions by means of magnetron sputtering. The effect of sputtered columnar nano-grain structure on the oxidation behavior of the low-Cr alloy was investigated in air at 800 ℃. It was found that the columnar nano-grain structure significantly lowered the oxidation rate and changed the surface oxide structure of this alloy. The formation of a continuous Cr_2O_3 inner layer beneath the CoFe_2O_4 spinel outer layer on the sputtered nanocrystalline coating resulted in a remarkable improvement in oxidation resistance compared to the cast low-Cr alloy.