Composition related magnetic properties and coercivity mechanism for melt spun [(La0.5Ce0.5)1−xREx]10Fe84B6 (RE=Nd or Dy) nanocomposite alloys

• Properties and coercivity mechanism were discussed for (LaCe)FeB nanocomposites.
• Dy substituting LaCe increased the coercivity but reduced the remanence.
• Nd substitution enhanced the coercivity, remanence and energy product.
• Dominant coercivity mechanism observed in Dy substituted sample is nucleation.
• Pinning mechanism was observed in Nd substituted sample.

Room temperature magnetic properties and coercivity mechanisms for nanocomposites [(La0.5Ce0.5)1−xREx]10Fe84B6 (RE=Nd or Dy; x=0, 0.3, 0.5, and 0.7) alloys prepared by melt-spinning have been investigated. Nd and Dy substitutions can improve the hard magnetic properties, especially the coercivity of [(La0.5Ce0.5)]10Fe84B6 alloy. The largest values of intrinsic coercivity Hc and maximum energy product (BH)max for the Dy substituted alloys are 714 kA/m and 41 kJ/m3, respectively, whereas for Nd substituted alloys, Hc=365 kA/m and (BH)max=120 kJ/m3 were obtained for x=0.7. The different elevated temperature behaviors were also found for Nd and Dy added alloys. The composition dependent coercivity mechanisms for Dy and Nd substituted alloys are evident based on the temperature dependence of coercivity described by domain wall pinning and reverse domain nucleation models. It is found that the domain wall pinning mechanism is possibly responsible for [(LaCe)Nd]FeB alloys while reverse domain nucleation is more likely responsible for[(LaCe)Dy]FeB alloys.