Below is a “from‑scratch” permanent‑magnet concept that stitches together the best lessons from tetragonal Fe‑Co physics, rapid ordering tricks, and exchange‑spring nanocomposites. I kept every element earth‑abundant, readily recyclable, and friendly to mass‑production metallurgy.
Target | Value | Rationale |
|---|---|---|
Uniaxial anisotropy | ≥ 1 MJ m⁻³ | at least ferrite‑class coercivity |
Saturation induction | ≥ 2 T | push remanence beyond 1.5 T |
(BH) | 30 – 40 MGOe | close the gap to Nd‑Fe‑B mid‑grade grades |
Curie temperature | ≥ 550 °C | EV‑motor safe margin |
No critical elements | Fe, Co, V, N, B, Cu | price < $ 10 kg⁻¹ |
FeCoV
V + N stabilise the bct lattice and lock in even in 100 nm films and bulk foils.
Pure bct‑FeCo is predicted to rival or exceed FePt’s anisotropy while carrying 50 % more magnetisation.
Fe‑Co‑B (bcc) shells 3–5 nm thick around each hard grain
Give an extra 0.4–0.5 T to through exchange‑spring coupling.
B lowers grain‑boundary mobility, freezing grain size near 20 nm.
Cu/VC nano‑precipitates (<2 vol %) form during aging and immobilise domain walls.
Induction melt Fe‑Co‑V master alloy, over‑doped with 0.5 wt % B.
Gas‑atomise into ≤ 30 µm powder; high quench rate preserves metastable bct nuclei.
Reactive nitriding: NH flow, 450 °C, 30 min → N uptake, full tetragonality.
Surfactant‑assisted ball mill 2 h → 15–25 nm crystallites.
Spark‑plasma sinter + 2 T field: 550 °C, 5 min → dense, c‑axes aligned bulk.
Age 400 °C, 1 h → Cu/VC precipitates and stress relief.
Every step is conventional powder‑metallurgy equipment; cycle time < 2 h.
Parameter | Estimate | How we get there |
|---|---|---|
2.0 – 2.1 T | bct Fe‑Co base + 30 % soft phase | |
That slots the alloy squarely between MnAlC (≈8 MGOe) and today’s mid‑range Nd‑Fe‑B (35–45 MGOe)—without Dy, Nd or Sm.
Element | Job |
|---|---|
Fe + Co | delivers the world‑record saturation magnetisation of FeCo |
XRD (Cu Kα) to confirm c/a > 1.2 after nitriding.
TEM + EELS grain‑size and phase mapping.
VSM loops @ 300 K for &
If loops match the table above, scale gas‑atomisation to 50 kg lots and feed existing powder‑bed fusion printers for net‑shape motor rotors.
data_HyperionX_bct _symmetry_space_group_name_H-M 'I 4/mmm' _symmetry_Int_Tables_number 139 # ---------------------------------------------------------------------- # Lattice parameters (metastable bct Fe‑Co‑V‑N‑B) # ---------------------------------------------------------------------- _cell_length_a 2.850 _cell_length_b 2.850 _cell_length_c 3.480 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 # ---------------------------------------------------------------------- # Symmetry operations (standard for I4/mmm) # ---------------------------------------------------------------------- loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, -y, z' '-y, x, z+1/2' ' y, -x, z+1/2' 'x, y, -z' '-x, -y, -z' '-y, x, -z+1/2' ' y, -x, -z+1/2' # ---------------------------------------------------------------------- # Atom sites with mixed occupancies # ---------------------------------------------------------------------- loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy Fe_M1 Fe 0.000 0.000 0.000 0.275 # 2a site (mixed Fe/Co/V total occ = 1.0) Co_M1 Co 0.000 0.000 0.000 0.150 V_M1 V 0.000 0.000 0.000 0.035 Fe_M2 Fe 0.000 0.000 0.500 0.275 # 2b site Co_M2 Co 0.000 0.000 0.500 0.150 V_M2 V 0.000 0.000 0.500 0.035 N_I1 N 0.000 0.500 0.250 0.030 # 4d interstitials (light elements) B_I1 B 0.000 0.500 0.250 0.050 N_I2 N 0.500 0.000 0.250 0.030 B_I2 B 0.500 0.000 0.250 0.050 N_I3 N 0.000 0.500 0.750 0.030 B_I3 B 0.000 0.500 0.750 0.050 N_I4 N 0.500 0.000 0.750 0.030 B_I4 B 0.500 0.000 0.750 0.050
A tetragonal Fe‑Co‑V‑N hard phase exchange‑coupled to Fe‑Co‑B soft shells should hit ~35 MGOe with nothing rarer than vanadium, survive 500 °C, and roll straight off a powder‑metallurgy line. That’s a permanent magnet worth chasing—and far more promising than cubic Fe(B,C) or W‑doped variants.
1.2 – 1.5 MJ m⁻³ |
V + N tetragonality |
0.9 – 1.1 T | single‑domain grains ≈ 20 nm + precipitate pinning |
1.5 – 1.7 T | exchange‑spring boost |
(BH) | 32 – 40 MGOe | micromagnetic modelling & scaling law from nanocomposites |
~900 K | high‑FeCo matrix |
V | expands the c‑axis and helps lock the bct lattice |
N (interstitial) | amplifies tetragonality and Ku while slightly boosting resistivity |
B | glass‑former; refines grains; bumps resistivity; part of soft shell |
Cu | forms nanoscale precipitates that immobilise domain walls without diluting Ms |
Pulsed‑field testing to 10 T for irreversible field.
High‑T ageing (up to 200 °C for 1000 h) to benchmark thermal demagnetisation.
Worked on this with OpenAI's o3 model. It's pretty exciting. It seems the model has some decent intuitions about what would make a good candidate, including which elements and how to structure them.
Later in this work we started to come up with ways to take a rough outline like this post and actually get to a "SUN" material (stable, unique, novel).
We need to assess things like:
≤ 50–70 meV atom⁻¹ to be synthesizable
Relax and converge total energy to < 1 meV/atom and stress < 0.5 kbar
Ensure no imaginary modes in phonon spectra
And more. I'm going to start working on building out the materials API from Hermes with these functionalities so we can start working on a more agentic and automated process of coming up with new designs and testing them.