OXIDATION OF PURE YTTRIUM AND TWO Fe-Y ALLOYS IN 0.1MPa O_2 AT 600～800℃

The oxidation of two iron\|based alloys containing 15wt% and 30wt% yttrium as well as pure yttrium has been studied in pure oxygen of 0.1 MPa.Both alloys formed an external scale containing a mixture of iron and yttrium oxides and double Fe\|Y oxides.A region of internal oxidation of yttrium was formed in the alloys.The microstructure of the internal oxidation region followed closely that of the original alloys and there was no any yttrium depletion in the internal oxidation region.These results are examined by taking into account the limited solubility of yttrium in iron and the presence of intermetallic compounds in the alloy.