Influence of Yttrium on Growth Stresses Developed in FeO Scales Formed on Pure Iron at 800 C.

In-situ XRD stress determinations have been performed during pure iron oxidation. The compressive stress, initially present in a blank substrate, due to surface preparation, is completely released at 400*C. On yttrium implanted iron no stress is initially present in the substrate. Under the oxidising conditions, the in-situ compressive stress level determined in the FeO scale during oxidation is not strongly dependent upon the presence of implanted yttrium. On blank and implanted specimens, the compressive stress varies from -400+- 80 MPa to -150 +- 100 MPa during the 30 hours oxidation. However, after cooling to room temperature, blank specimens show compressive residual stresses, implanted samples show residual tensile stress. The results also indicate that epitaxial relationships between the oxide scale and the substrate can be a source of stress in an oxide scale. A way to lower compressive stress can be the use of yttrium ion implantation.

BUSCAIL H.;  STROOSNIJDER Marinus Frederik;  JACOB Y.P.;  SCIORA E.; 

1998-11-09

JRC17674