Investigation of fabrication of Mn-Ga-Al/Fe-Co nanocomposite hard magnetic materials

Abstract

Mn-Ga-Al/Fe-Co nanocomposite hard magnetic materials were combined from Mn 65 Ga 20 Al 15 hard magnetic and Fe 65 Co 35 soft magnetic phases. The nanoparticles of hard and soft magnetic phases were fabricated by using high energy ball milling method with milling times of 8 h and 32 h to have size of about 50 nm and 70 nm, respectively. The hard and soft magnetic phases were then mixed together for 1 h with different weight fractions of Fe 65 Co 35 soft magnetic phase from 5 to 20%. The nanocomposites show quite good exchange-spring coupling of hard and soft magnetic phases. Saturation magnetization (M s ) and coercivity (H c ) of the nanocomposites strongly depend on the weight fraction of the soft magnetic phase. The M s increases rapidly, while the H c decreases with increasing the fraction of the soft magnetic phase. With appropriate fabrication conditions, the Mn-Ga-Al/Fe-Co nanocomposites can possess M s > 50 emu g −1 and H c > 9 kOe. Maximum energy products, (BH) max , above 4 MGOe have been achieved for this kind of rare earth-free hard magnetic materials.