Effect of Ga substitution on the structure and magnetic properties of melt-spun Pr3(Fe,Co,Ti)29 system

Melt-spun alloys of Pr3(Fe0.7Co0.3)27.5Ti1.5, Pr3(Fe0.6Co0.4)27.5Ti1.5, and Pr3(Fe0.5Ga0.1Co0.4)27.5Ti1.5 prepared at linear wheel speeds of 20, 30, and 40m∕s were found to contain nanocrystalline, a mixture of nanocrystalline and amorphous, and mostly amorphous phases, respectively. Grain sizes of <10nm were observed for the crystalline phases. Annealed alloys showed an increase in grain size to 15–20nm. The Curie temperature (TC) values observed in melt-spun alloys were lower than those observed in fully crystalline alloys. A reduction of ∼55°C in TC was observed for the Pr3(Fe0.7Co0.3)27.5Ti1.5 composition compared to ∼15°C for Pr3(Fe0.6Co0.4)27.5Ti1.5. For the Ga substituted alloy with Co=0.4, a large difference of ∼50°C in TC was noted. MS values of 41 and 35emu∕g were observed in alloys with Co=0.4 and Ga=0.1, and Co=0.4, respectively, at room temperature. Ga substitution increased the anisotropy field value, HA, but lowered the intrinsic coercivity value, Hci. In the alloys with Co=0.4 and Ga=0.1, ...