Investigation of crystallization process in isotropic rare-earth-rich (Nd or Pr)–Fe–B films

In this paper, the relationship between the initial crystalline behavior and annealing conditions in pulsed laser deposition (PLD)-made Nd-Fe-B and Pr-Fe-B films with rare-earth-rich composition is discussed. The films with rare-earth-rich compositions are prepared via PLD. An annealing process is necessary to obtain the crystalline 2-14-1 phase of hard magnetic properties because all the as-deposited films have an amorphous structure. In conventional annealing, the initial crystallization of the Pr2Fe14B phase occurred at lower temperatures compared with that of the Nd2Fe14B phase, indicating that the annealing temperature of the initial crystallization of the Pr2Fe14B phase was lower than that of the Nd2Fe14B phase. Considering the same crystallization temperature in both the phases, the melting points of both rare-earth elements, Nd and Pr, are considered to relate to the initial crystallization behavior. We also confirmed that the annealing time for Pr2Fe14B phase formation was shorter than that for Nd2Fe14B phase formation.