Development of a Strong Magnets with the high anisotropy by using HDDR and micro alloying process

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The main aim of this study is to elucidate the role of small additives on the enhancement of magnetic anisotropy of Nd_2Fe_<14>B based magnets during Hydrogenation, Disproportionation, Desorption and Recombination (HDDR) process.The following results are obtained through this researching project.1) Nb in Nd_<12.5>Fe_<bal>Ga_<0.3>Nb_<0.2>B_<6.2> forms FeNbB compound in the as-cast state and it is stable through HDDR process.2) Ga in Nd_<12.5>Fe_<bal>Ga_<0.3>Nb_<0.2>B_<6.2> preferentially occupies Fe(4c) site at the homogenized state and transfers to bcc Fe at the disproportionated state.3) At the beginning of recombination stage, Nd_2Fe_<14>B forms preferentially at the place where Ga is included.4) From this result we can infer that Ga is included in bcc Fe near the grain boundary region and the recombination of Nd_2Fe_<14>B start from the grain boundary where Ga is included.5) Zr in homogenized Nd_<12.5>Fe_<bal>Zr_<0.5>B_6, which is prepared by arc melting forms ZrB and this ZrB compound is stable through HDDR process.6) Site preference of Zr in a melt-quenched Nd_<12.5>Fe_<bal>Zr_<0.5>B_6 ribbon differs from the sample prepared by arc melting ; Zr in melt-quenched Nd_<12.5>Fe_<bal>Zr_<0.5>B_6 occupies Nd(4f) site rather than Zr site in ZrB for the sample prepared by arc melting.