Microstructure and Improved Coercivity of Mn<sub>1.33</sub>Ga Nanoflakes by Surfactant-Assisted Ball Milling

Abstract

In recent years, Mn x Ga alloys with tetragonal structure have attracted much attention because of the erratic fluctuation of rare earth supply and especially the tunable magnetic properties from fer-rimagnetic to ferromagnetic by varying Mn content. It is theoretically estimated that MnGa compound in L1 0 structure owes high anisotropy constant K u of 26 Mergs/cm3 and magnetization Ms of 845 emu/cm3, and thus can be regarded as a potential candidate for rare-earth-free permanent magnets [1-2]. At present, surfactant-assisted high-energy ball milling (HEBM) method has been regarded as one of the effective ways to realize high coercivity for magnetic materials with large anisotropy. It was reported [3-4] that high-aspect-ratio single-crystal or textured polynanocrystalline flakes of Sm-Co-based permanent magnetic materials with a submicron or nanosize thickness and high coercivity can be achieved. In this study, textured rare-earth-free Mn 1.33 Ga polycrystalline nanoflakes were prepared by surfactant-assisted HEBM in heptane with 15wt. % oleic acid (OA), and the effects of milling time on structure and magnetic properties were also investigated.