High Performance Pr_2(Fe, Co)_(14)(C, B)-type Nanocomposite Ribbons with Ti-substitution

摘要

The phase evolution, microstructure and magnetic properties of Pr_(9+x)Fe_(73-x)Co_(10) B_4C_4 and Pr_(9+x)Fe_(17-x)Ti_2Co_(10)B_4C_4(x=0, 0.5 1, 1.5) melt-spun ribbons have been investigated. All ribbons are mainly comprised of the 2:14:1, 2:17 and a-Fe phases. For the group of Pr_(9+x)Fe_(73-x)Co_(10)B_4C_4 ribbons, the coercivity increases with increasing of x while the remanence decreases with increasing of x. Optimal magnetic properties of (BH)_(max)=12.5MGOe for the Ti-free group have been obtained at x=1.5. When 2at. %Ti is substituted for Fe, the magnetic properties are remarkably enhanced. The coercivity and squareness of demagnetization curve of the Ti-substitution ribbons are substantially improved without a sacrifice of remanence (except for x=0), even the remanence obviously increasing at x=1.5. In this study the optimal magnetic properties when B_r=9.6kG, _iH_c=10.2kOe, (BH)_(max)= 17.4MGOe have been obtained in Ti-substituted Pr_(10.5)Fe_(69.5)Ti_2Co_(10)B_4C_4. Ti-substitution suppress the formation of 2:17 phase and prior growth of α-Fe phase during melt-spinning and annealing process, which optimize the grain size and the volume fraction magnetically of hard phase and soft phase. As a result, the intergranular exchange coupling substantially increases. These are the main reasons that the magnetic properties increase with increasing of Pr in Ti substituted Pr_(9+x)Fe_(71-x)Ti_2Co_(10)B_4C_4 (x=0-1.5) ribbons.