Phase equilibria of the Fe–Cr–Ni ternary systems and interfacial reactions in Fe–Cr alloys with Ni substrate

Abstract

Fe–Cr–Ni ternary systems are of fundamental importance for solid oxide fuel cell (SOFC) applications. Fe–Cr alloys are commonly utilized materials as interconnect materials and yttria-stabilized zirconia (YSZ) doped with Ni is the common anode materials. In this study, isothermal sections of the Fe–Cr–Ni ternary system at 750 and 850 °C were experimentally determined. In addition, the interfacial reactions in several Fe–Cr alloys with Ni were investigated. No ternary intermetallic compounds (IMCs) can be found at 750 °C, and only one ternary IMC, σ phase, existed at 850 °C in the Fe–Cr–Ni ternary systems. In the Fe–16 wt%Cr and Fe–25 wt%Cr couples, layer-shape α and γ phases, and the island-shape α′ phase were formed on the Fe–Cr/Ni interface at 750 °C. As the reaction temperature rose to 850 °C, only the α′ and γ phases can be observed. In Fe–80 wt%Cr and Fe–94 wt%Cr couples, α′ and γ phases are formed on the Fe–Cr interface at both 750 and 850 °C. The thickness of all reaction couples increased with longer reaction time and less Cr content in Fe–Cr alloys. All the IMCs growth mechanism can be described by the parabolic law. The IMCs growth is diffusion controlled.