Effect of doping Al-Cu-Fe alloy on the microstructure and magnetic properties of annealed Nd-Fe-Co-B ribbons

Doping 1 wt% Al89.5Cu9.7Fe0.8 alloy promotes the phase separation of Nd13.53Fe74.89Co5.54B6.04 alloy, forming the unique microstructure of small Nd-rich particles embedded in the large equiaxed Al-Cu-Fe-rich grains with the same Nd2Fe14B-type structure. Low-temperature annealing at 650 degrees C-710 degrees C improves the disorder degree of Nd2Fe14B-type phases and reduces the composition difference between different phases. Correspondingly, the large amorphous regions reduce to similar to 20 nm small particles, and the small amorphous regions are crystallized into nanoclusters or nanoparticles. When the annealing temperature exceeds 750 degrees C, the grain composition is thoroughly homogenized, and the grains begin to overgrow. Al-Cu-Fe addition improves the thermal stability of some Fe-rich amorphous particles and makes them difficult to crystallize. Compared to the as-spun ribbons, annealing at 710 degrees C increased the coercivity by 72%, the remanence by 34%, and the maximum magnetization by 2.0%. At the same time, the corresponding microstructure evolution models are established.

Automated summary

Doping 1 wt% Al89.5Cu9.7Fe0.8 alloy promotes the phase separation and microstructure evolution of Nd13.53Fe74.89Co5.54B6.04 alloy. Low-temperature annealing improves the disorder degree, reduces composition difference between phases, and results in the formation of small particles or nanoparticles.