Advances in the development of corrosion and creep resistant nano-yttria dispersed ferritic/martensitic alloys using the rapid solidification processing technique

In this study, the production of ODS based on T91 is examined by adding a 0.3 wt% colloidal Y2O3 dispersion to a T91 steel melt in combination with metallic yttrium (YM). The production of the following systems is evaluated: T91-Y2O3, T91-YM and T91-YM-Y2O3. At first, it was found that when YM is added to a steel melt, internal oxidation occurs. Furthermore, it was shown that the T91 system with addition of Y2O3 in combination with rare-earth metal YM, creates a homogeneously dispersed ODS T91 material. Moreover, the role of YM as a possible surface active element lowering the surface tension at the contact interface is studied. High-temperature contact angle wetting tests between Y2O3 ceramic substrates in contact with an T91 and a [T91+YM] melt, combined with auger-electron spectroscopy (AES), indicate the influence of YM on the surface activity of Y2O3 in contact with T91. After YM addition, the contact angle between T91 and the Y2O3 substrate lowers down to angles below 90°.