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Two FeCrAlZr alloys are fabricated by twin‐roll strip casting (TRSC) and ingot casting (IC), and different Zr distributions are formed. After cyclic oxidation tests at 1200 °C for 200 h in air, it is found that the scale spallation resistance in the FeCrAlZr alloy is improved by homogenizing the Zr distribution by TRSC. To understand the improvement in oxidation resistance, the composition and microstructure of the thermally grown scales are investigated. During oxidation, Zr diffuses toward the scale and forms ZrO2 particles in the scale and at the surface of the oxide scale. Meanwhile, the outward diffusion of Zr inhibits the formation of interfacial voids and S segregation regardless of Zr distribution. However, the TRSC sample with a more uniform Zr distribution can form the high‐density oxide penetrations, keying the scale to the matrix and improving scale adhesion. The Zr fluxes toward the scales are calculated to explain the difference in the distribution of oxide penetrations in the TRSC and IC samples during oxidation.

Herein, the effect of different contents of Cr on the isothermal structure transformation of FeO is systematically studied by a thermogravimetric analyzer, and it is found that the temperature range of eutectoid transformation of FeO in Fe–Cr alloy is 300–500 °C. Combined with the experimental data, the kinetic model of isothermal phase transformation of FeO is established based on Johnson–Mehl–Avrami–Kolmogorov equation, and the time–temperature–transformation curve of isothermal transformation of FeO is predicted, which follows the law of C curve, and the C curve shifts backward with the increase of Cr content. Therm‐calc thermodynamic software calculates the Fe–O phase diagrams of different Cr contents. Combined with the experimental results, the effect mechanism of Cr content on FeO eutectoid transformation is clarified. With the increase of Cr content, the stability of FeO decreases, and under the same isothermal temperature and time, high Cr content has greater undercooling, a higher driving force of phase transition, and the starting time of eutectoid transformation is earlier than that of lower Cr content.

FeCrAlY alloys are widely used as thin‐gauge catalyst carriers for automotive exhaust gas purification. However, they exhibit low ductility due to coarse Fe–Y phases in the alloys, which decreases the carrier yield. To improve the plasticity of the alloys, a novel method for fabricating FeCrAlY alloys using twin‐roll strip casting (TRSC) is proposed. It is found that the plasticity of the FeCrAlY alloy is significantly improved by TRSC compared to conventional ingot casting. Then, to understand the mechanism of plasticity improvement, the microstructures of the alloys are investigated. The Fe–Y phases and grains are significantly refined by TRSC due to its characteristics of subrapid solidification. In addition, the TRSC samples produce several low‐Σ coincidence site lattice (CSL) boundaries, and some of these CSL grain boundaries are inherited by the cold‐rolled sheets. The impact characteristic of steel liquid in the TRSC is the major reason for the formation of CSL grain boundaries. The finer microstructure and greater number of low‐Σ CSL boundaries in the TRSC samples result in strong resistance to fracture, which improves the plasticity of the FeCrAl alloys.

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