High coercivity in Mn-Ga-Cu alloys

Abstract

Mn-Ga-Cu alloys were produced by melt-spinning and subsequent annealing. The coercivity of the Mn-Ga-Cu alloys was dependent on the Cu content and the annealing conditions. The coercivity of the Mn65Ga20Cu15 alloy annealed at 573 K for 10 h, iHc = 23.8 kOe, was comparable to that of rare-earth-based magnets. The hard magnetic phase of the Mn65Ga20Cu15 alloy was found to be fine D022-Mn3Ga grains, formed from the fcc phase during annealing.

Structure and magnetic properties of melt-spun Mn-Ga-Cu-Al ribbons

“…Thus, the annealing regime with temperature of 275 °C − 300 °C and time of 10 h − 15 h, is effective for enhancing hard magnetic parameters of the alloy ribbons. The obtained results are in good agreement with those reported by T. Saito et al for Mn 65 Ga 35-x Cu x alloy ribbons [40]. They showed that, the coercivity strongly depends on Cu concentration from 0 to 20% and annealing temperature from 200 °C to 600 °C.…”

“…However, the obtained M s value is rather low, only 3 emu g −1 . In other studies [40,45], the substitution of Al for Ga in the Mn-Ga based alloy ribbons formed a phase with new cubic structure with space group P2 1 3 or P4 2 32 in addition to the D0 22 ferrimagnetic phase. The coercivity in the Mn 65 Ga 15 Al 20 ribbon annealed at 700 °C for 1 h is increased from 5 kOe to 9.1 kOe by contribution of the D0 22 phase.…”

“…The creation of this desired phases strongly depends on composition and fabrication conditions of the alloy. Up to now, various forms of Mn-Ga alloys including bulk, ribbon, film and nanoparticle have been fabricated by respective methods of arc-melting, rapidly quenching, sputtering and high energy ball milling [35][36][37][38][39][40][41][42][43][44][45]. With bulk samples prepared by arc-melting method, the desired magnetic phases are usually formed with long annealing time, up to several days [28,35,36].…”

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

“…Figure 4(b) shows the hysteresis loops of the samples annealed at 650 • C for various times. The results of our hard magnetic properties obtained on these Mn-Ga-Al samples are similar to those of other research groups on the same material [20,23,26]. From the obtained results, we selected the annealing temperature of 650 • C and time of 15 min for the hard magnetic phase.…”

“…According to theoretical calculations, nanocomposite hard magnetic materials might have a maximum energy product (BH) max more than 100 MGOe [18] based on a combination of strong coercivity of hard magnetic phases and high saturation magnetization of soft magnetic phases. Recently, the Mn-Ga based hard magnetic materials have been attracting research interests as a new hard magnetic phase for the nanocomposite materials [19][20][21][22][23]. By adding elements such as Cu, Fe, Al… the D0 22 -type hard magnetic phase is formed more easily and its coercivity can exceed 10 kOe, high enough for coupling with the soft magnetic phase.…”