An Investigation on Nanocrystalline TbCu7-Type SmCo6.4Si0.3Zr0.3C0.2Alloys With Sm Partially Substituted by Various Light and Heavy Rare Earth Elements

Conventional Sm–Co-based alloys have low glass forming ability, and thus are difficult to quench to nanocrystalline structure by rapid solidification. In this paper, nanocrystalline [Sm, rare earth (RE)] Co _6.4 Si _0.3 Zr _0.3 C _0.2 (RE = Ce, Sm, Gd, Ho, and Er) alloys have been obtained by melt spinning after compositional modification, as prepared alloys have a microstructure consisting of TbCu ₇ -type SmCo ₇ -based nanocrystals with the mean size of approximately 20 nm surrounded by a soft amorphous phase and a cobalt phase. After annealing at 600 °C for 1 h, the alloys were well crystallized and the grains grew up to ~100 nm. Both the coercivity and the remanence have been enhanced significantly by annealing. The effects of the substituted RE elements on the magnetic properties and thermal stability were investigated. An annealed Sm _0.8 Er _0.2 Co _6.4 Si _0.3 Zr _0.3 C _0.2 alloy showed the highest remanence of 0.59 T and (BH) _max of 58.8 kJ/ $\text{m}^{3}$ . Excellent thermal stability with the remanence temperature coefficient $\alpha $ of −0.0178%/°C and −0.0778%/°C at temperature range of 27 °C~200 °C and 27 °C~400 °C, respectively, was also obtained.