| Title |
Research Paper - Environment - : Role of La on High Temperature Oxidation Behavior of Fe - 20wt%Cr - 5wt%Al alloys |
| Authors |
이기선(Kee Sun Lee); 신용창(Yong Chang Shin); 오규환(Kyu Hwan Oh); 박원욱(Won Wook Park); 나형용(Hyung Yong Ra) |
| Abstract |
Reactive element addition, La, to Fe-Cr-Al alloy improves the high temperature oxidation resistance. The object of present study is to examine the role of La. La segregates at grain boundary of metal substrate and is not present in oxide layer during the high temperature oxidation. La addition increases oxidation duration time because Al depletion rate is reduced. Segregation of La decreases the outward diffusion of Al through grain boundary of metal. α-alumina crystal has grown as a columnar grain on metal substrate surface. The oxide/metal interface moved into metal substrate. In case of no La addition, outward diffusion of Al along the metal substrate grain boundary give rise to heterogeneous nucleation and growth of α-alumina crystal on the grain boundary of metal surface. Consequently α-alumina exhibited planar coarse morphology. The major rode of La in Fe-Cr-Al alloy is to suppress the Al diffusion from metal substrate, to change morphology of α-alumina and subsequently to enhance the oxidation resistance. |