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

In this work, we investigated structure and magnetic properties of Mn65Ga20Al15-xCux (x = 0, 5, 10 and 15) alloy ribbons prepared by melt-spinning method combined with annealing. The annealing temperature was varied from 250 & DEG;C to 350 & DEG;C, and the annealing time was changed from 5 h to 20 h. Concentration of Cu and annealing process significantly influence on the formation of the desired phases in the alloy ribbons. The D0(22)-type Mn3Ga crystalline phase with the hexagonal structure, which characterizes hard magnetic property of Mn-Ga based alloys, is enhanced after an appropriate annealing process. The change of grain size after annealing also contributes to the increased coercivity of the alloy ribbons. The highest coercivity of 12.9 kOe and saturation magnetization of 18.7 emu g(-1) are achieved on the alloy ribbons with Cu concentration of 10%. The simultaneous enhancement of these magnetic parameters has an important significance for application possibility of the Mn-Ga based alloys.