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

Nguyen Mau Lam, Do Thi Thuy, Pham Ha Trang, Nguyen Hoai Anh, Nguyen Thi Luyen, Nguyen Thi Hien, Ngo Thi Truong, Pham Thi Thanh, Nguyen Hai Yen, Nguyen Van Duong, Nguyen Huy Ngoc, Duong Dinh Thang, Tran Minh Thi and Nguyen Huy Dan

Abstract

Mn-Ga-Al/Fe-Co nanocomposite hard magnetic materials were combined from Mn₆₅Ga₂₀Al₁₅ hard magnetic and Fe₆₅Co₃₅ 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 Fe₆₅Co₃₅ 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