Magnetic properties of Fe16−x(Ta/W)xN2 ternary alloy: first principles and atomistic simulations

Abstract

Using the first principles method, we explored the magnetic properties of Fe16−x(Ta/W)xN2 alloy. We calculated the alloy formation energy, dynamical and thermal stabilities and proved the possibility of materialization of Fe16−x(Ta/W)xN2 alloy. The Fe14Ta2N2 had a Curie temperature of 1020 K while it was 950 K in Fe14W2N2. We found greatly enhanced uniaxial anisotropy in ternary alloy systems. Particularly, the Fe14W2N2 alloy has a uniaxial anisotropy constant of 2.68 MJ m−3 which is almost a five times enhancement of the value of 0.57 MJ m−3 in the Fe16N2. The increase in the uniaxial anisotropy resulted in an enhancement of the coercive field (HC). The Fe14W2N2 had a coercive field of 27 kOe at 300 K and this is comparable to that of 25.6 kOe in Dy-doped Nd based magnet. Besides, the (BH)max of 54.5 MGOe in Fe14W2N2 alloy was even larger than the value of 40 MGOe in Dy-doped Nd-based magnet. Overall, we propose that the Fe16−x(Ta/W)xN2 can be a potential rare-earth-free permanent magnet.