Preparation of MnAlC flakes by surfactant-assisted ball-milling and the effects of annealing

Abstract

An alternative approach for preparing anisotropic MnAlC powders is reported. [001] textured MnAlC flakes with various sizes and thicknesses were fabricated by surfactant-assisted ball-milling (SABM) of bulk ingots. After ball-milling for 8 h the flakes have thicknesses below 200 nm and aspect ratios as high as 10 ²∼10 ³. After being annealed at suitable temperatures, both bulk and SABMed powders can transform from ∊-phase to τ-phase completely. C-doping cannot prevent the decomposition of the τ-phase into the β+γ ₂ phases after annealing at above 500°C. The magnetic properties are strongly dependent on both the fraction of the τ-phase and the thickness. A high coercivity of ∼242.8 kA m ⁻¹ has been achieved in SABMed powders. The coercivity value is 128.8% higher than the experimental value for bulk materials.