Microstructural Considerations on the Magnetostriction Enhancement in Dy Doped Fe81Al19 Alloys

Abstract

This study explores the structural and microstructural effects of Dy doping on the magneto-crystalline properties of (Fe₈₁Al₁₉)_100-xDy_x (x = 0, 0.05, 0.10, and 0.15) alloys prepared by the arc melting technique. All compositions exhibited a single-phase body-centered cubic (BCC) A2 structure, corresponding to the Im $$ m space group (No. 229). Progressive Dy incorporation led to an increase in lattice parameters and promoted the development of preferential orientation, particularly along the (200) and (310) crystallographic planes, as confirmed by inverse pole figure analysis. A total magnetostriction (λ_∥-λ_⊥) enhancement is found in all doped samples, increasing from 28 ppm for the undoped alloy to a maximum of 92 ppm in the x = 0.10 composition. Further Dy additions did not yield additional improvements, suggesting a change in the grains of the microstructure accompanied by defect generation. Additionally, significant variations in average crystallite shape were found, mainly due to growth in the (200) plane, indicating stress accumulation. The magnetostriction enhancement is primarily attributed to a reduction in average maximum strain and, secondary, to the preferential orientation development. The x = 0.10 alloy exhibited a favorable (200) preferential orientation fraction of 57.3% and the lowest average maximum strain value of 55.3×10⁻⁴.