Temperature dependence of abnormal grain growth and high magnetostriction in Goss-oriented Fe-Al thin sheets

Abstract

In this paper, we investigate grain growth behaviors in Fe-Al-NbC rolled sheets annealed under a sulfur atmosphere at temperatures of 1000–1300 °C for NbC additions of 0.75%, 1.0%, and 1.5%. In Fe80Al20 sheet plus 0.75% NbC, abnormal grain growth (AGG) occurred at higher temperature than 1150 °C. Large single (011) grains that covered 74%–90% of sample surface were fully grown at temperatures of 1200–1300 °C. For these samples, the remaining 10%–26% of the surface was comprised of small isolated island-like grains that were dispersed throughout the single grain Goss matrix. The single-grain-oriented Fe-Al sheet sample annealed at 1250 °C for 5 h exhibited magnetostriction of 133 ppm along the rolling direction (RD). A maximum magnetostriction value of 143 ppm along the RD was obtained in samples annealed at 1200 °C for 24 h. Of particular interest is that the magnetostriction response along ⟨100⟩ in these samples shows 177 ppm, approaching ∼94.4% of the magnetostrictive performance of single crystal at 19.5 at. % Al. In addition, we observed that the temperature at which the onset of AGG occurred increased with increasing the NbC content, which can be explained by an enhanced particle pinning force.