THE OXIDATION-RESISTANCE PROPERTIES OF IRON-BASED SUPERALLOYS BETWEEN 1473 AND 1523K

摘要

To obtain high strength values, the alloying element Al is removed in iron-based alloys, which reduces the oxidation resistance during exposures in air at 1473-1523K. To improve the oxidation resistance, a small amount of alloying element Al will be added to an iron-based alloy, with modified quantities of elements Ni and Cr. These changes to the alloy composition have not reduced the strength of the alloy significantly. X-diffraction, optical and electron microscopy have been used to inspect the structure of the oxidation layer. For the alloy that didn't contain Al, the layer of oxidation is very thickness and mainly consists of Fe_2O_3, NiFe_2O_4 and spinel(Cr_2NiO_4 and CoCr_2O_4). The structure of the oxidation layer is not made up of a dense scale , but with internal oxidation product. The results of this work show that the diffusion of O effectively in the iron-based alloys without the adding of Al.