Projekt- und Abschlussarbeiten

Magnetic isolation of hard magnetic grains with an intergranular phase is a key factor in obtaining high coercivity, which has been established in the microstructure of Nd-Fe-B magnets owing to the phase equilibrium of hard magnetic Nd2Fe14B with a low melting point phase [1,2]. SmFe12-based compounds exhibit superior intrinsic magnetic properties at magnet operating temperature compared with Nd2Fe14B. However, the inability to achieve an optimal microstructure similar to Nd-Fe-B in SmFe12-based magnets remains the main bottleneck for realizing large coercivity (Hc) and remanence. Our preliminary results in (Sm,Zr)(Fe,V,Ag)12 bulk alloy shows that we can separate the 1:12 grains with Sm-Ag intergranular phase while keeping the phase stabilizer V minimum (Fig 1). In this project, we will apply grain refinement procedure (melt spinning and ball milling) on (Sm,Zr)(Fe,V,Ag)12 bulk alloy to realize Hc.

(1) In the First step, the experimental condition will be optimized for (Sm,Zr)(Fe,V,Ag)12 bulk to obtain the microstructure in Fig. 1.

(2) In next step, melt spinning, excess of Sm, and annealing condition will be optimized for a particular composition of (Sm,Zr)(Fe,V,Ag)12.

(2) The microstructure, crystallographic and magnetic properties will be investigated.

(3) Once high coercivity is established further composition tunning (tunning Ag, addition of Co) will be perform to improve further their magnetization.

[1] P. Tozman et al. Scr. Mater. 194 (2021) 113686.

[2] P. Tozman et al. Acta Mater. 258 (2023) 119197.