Nucleation undercooling, solidification structures and magnetic properties of Nd9Fe85-xTi4C2Bx (x=10–15) magnetic alloys

Nd9Fe85-xTi4C2Bx (x=10–15) magnetic alloys were investigated by differential thermal analysis and X-ray diffraction analysis. The results showed that with the B content increasing from 10 at.% to 15 at.%, the liquidus temperatures TL of the alloys decreased from 1498.5 to 1472.5 K; the solidus temperatures TS of them increased from 1353.2 to 1358.3 K; and the nucleation undercooling of the alloy melts cooled at the rate of 40 K/min decreased from 122.8 to 95.9 K, resulting in the solidification structures consisting of Nd2Fe14B, Fe3B, α-Fe, Nd1.1Fe4B4 and TiC nanocrystallines. Furthermore, the Nd9Fe85-xTi4C2Bx (x=11, 13, 15) bulk alloys in sheet form with the thickness of 0.7 mm were prepared by copper mold suction casting and their solidification characteristics and solidification structures under sub-rapidly cooling rate were investigated. The results showed that partially amorphous structures were obtained in the as-cast bulk alloys and the amount of amorphous decreased with the increase of the B content. By annealing the as-cast bulk alloys at 923 K for 10 min, the nanocomposite microstructures composed with Nd2Fe14B, Fe3B and α-Fe nanocrystallines, which showed a single-phase hard magnetic behavior and enhanced magnetic properties, were achieved.

Graphical AbstractDTA heating and cooling curves of Nd9Fe85–xTi4C2Bx (x=10–15) alloy ingots (at heating and cooling rate of 40 K/min) with marking of characteristic temperatures (Nd9Fe71Ti4C2B14)Figure optionsDownload as PowerPoint slide