| Title |
A Study on the Formation of Oxide Layers on Fe - 36wt%Ni Invar Alloy |
| Authors |
이기훈(Ki Hoon Lee); 조준호(Joon Ho Cho); 이정중(Jung Joong Lee) |
| Abstract |
Oxide layers of an Fe-36wt%Ni Invar alloy produced by heating the specimen in air in the temperature range between 560℃ and 700℃ were investigated. According to XRD and AES analysis the oxide layers were composed of thin Fe₂O₃ on the surface, thick Fe_(3-x)Ni_xO₄(0≤x≤1) in the middle and thin NiO near the phase boundary. A thermodynamic evaluation has revealed that the Fe_(3-x)Ni_xO₄ layer is formed by the reaction of FeO with Ni which was enriched to a concentration above 70 at% through preferred oxidation of Fe at the initial stage of oxidation. NiO can be formed, on the other hand, by the reaction between Fe₂NiO₄ and Ni when the concentration of Ni reached over 90 at%. From the results of the XRD and AES analysis as well as the thermodynamic evaluation, the oxidation process of an Fe-36wt%Ni Invar alloy is proposed. |