Traditional rare earth iron boron permanent magnets have the disadvantage of Low coercivity, i.e. they tend to become demagnetized in an externally applied magnetic field.
Li and coworkers arc melted an industrial rare earth (RE) alloy with abundant La and Ce (RE100 = La30.6Ce50.2Pr6.4Nd12.8, ) with iron (99.9 wt.%), and iron-boron alloy (99.5 wt.%). The nominal composition of the melted material was RE13.6Fe78.4B8 . Also see MSE Supplis arc melters.
The melted allow was smashed into a powder under oxygen free conditions produced by pumping argon into a glove box. See MSE supplies high energy planetary mill for glove box.
Ball milling
- a hardened steel vial
- 12 mm diameter steel balls 12 mm diameter
- 1:16 100 μm Dy2O3 and Ca powders, powder:ball mass ratio with a particle size of
High-energy ball mill was performed with a rotation speed of 700 rpm for 5 h. See MSE supplies planetary mills..
Dopants added before milling:
- non doped material ⇒ 2.44 kOe
- 2.3 wt.% Ca ⇒ ~3 kOe
- 3 wt.% Dy2O3 (sam ⇒ ~ 4 kOe
- 7 wt.% Dy2O3 ⇒ ~7.5 kOe
- 2.3 wt.% Ca and 7 wt.% Dy2O3 ⇒ 11.43 kOe
Values in blue indicate the coercivity of the final product.
Annealing
the milled powders were annealed at 620–780 °C for 10 min in a vacuum environment (better than 1.3 × 10−3 Pa)
Li Y, Tian N, Fan X, You C, Pei W, Cheng Z. (2017) Synergetic Effect of Dy2O3 and Ca Co-Dopants towards Enhanced Coercivity of Rare Earth Abundant RE-Fe-B Magnets. Nanoscale Res Lett. 12(1):618 Free Paper
