Explosive shock processing of Pr2Fe14B-Fe.pdf

Explosive shock processing of Pr2Fe14B/
–Fe exchange-coupled nanocomposite bulk magnets Z.Q. Jin School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332; and Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 N.N. Thadhani,a) M. McGill, Y. Ding, and Z.L. Wang School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 M. Chen and H. Zeng IBM T.J. Watson Research Center, Yorktown Heights, New York 10598; and Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 V.M. Chakka and J.P. Liu Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (Received 31 August 2004; accepted 26 October 2004) Explosive shock compaction was used to consolidate powders obtained from melt-spun Pr2Fe14B/
–Fe nanocomposite ribbons, to produce fully dense cylindrical compacts of 17–41-mm diameter and 120-mm length. Characterization of the compacts revealed refinement of the nanocomposite structure, with approximately 15 nm uniformly sized grains. The compact produced at a shock pressure of approximately 1 GPa maintained a high coercivity, and its remanent magnetization and maximum energy product were measured to be 0.98 T and 142 kJ/m3, respectively. The compact produced at 4–7 GPa showed a decrease in magnetic properties while that made at 12 GPa showed a magnetic softening behavior. However, in both of these cases, a smooth hysteresis loop implying exchange coupling and a coercivity of 533 kA/m were fully recovered after heat treatment. The results illustrate that the explosive compaction followed by post-shock heat treatment can be used to fabricate exchange-coupled nanocomposite bulk magnets with optimized magnetic properties. I. INTRODUCTION A variety of nanocomposites consisting of hard mag- netic R2Fe14B (R
rare earth) and soft magnetic
–Fe or Fe3B phases are being extensively investigated due to their potentially high