SmFeN Magnet

The SmFeN magnet, based on the Samarium-Iron-Nitride (Sm₂Fe₁₇N₃) compound, emerged in the late 1980s through independent discoveries by Michael Coey and Takahiko Iriyama. This SmFeN magnet boasts high saturation magnetization, strong magnetocrystalline anisotropy, and a high Curie temperature, positioning it as a potential rival to Neodymium magnets. Since its discovery, researchers have viewed an SmFeN magnet as a candidate for high-performance permanent magnets, offering robust magnetic properties for advanced applications.

Despite over 25 years since its discovery, a fully dense SmFeN magnet remains uncommercialized due to Sm₂Fe₁₇N₃’s instability above 500°C, which prevents sintering or hot pressing. However, compression and injection molded SmFeN magnets are now produced, overcoming these thermal limitations and enabling niche applications, though not yet matching Neodymium’s widespread commercial success.

Several Japanese manufacturers have commercialized anisotropic bonded SmFeN magnets using Sm₂Fe₁₇N₃ powder and isotropic versions with SmFe₉N_x powder, achieving the highest magnetic properties among bonded magnets. A SmFeN magnet’s performance hinges on its magnetic powder’s quality, making the powder production process critical. By nitrogenating SmFe host powder, an SmFeN magnet gains exceptional magnetic strength, enabling its use in high-performance applications requiring precision and reliability.

Anisotropic SmFe host powders for a SmFeN magnet are crafted via melting-casting or reduction-diffusion using Samarium Oxide and Iron, while isotropic powders arise from rapid quenching of SmFe alloy. These distinct methods shape the magnet’s properties. Currently, Chinese SmFeN powder faces constraints in production capacity and stability, limiting its global impact compared to Japanese advancements.

Magnetic Properties of Injection Molded SmFeN Magnet

Material	Grade	Remanence Br		Coercivity Hcb		Intrinsic Coercivity Hcj		Max. Energy Product (BH)max		Temperature Coefficient %/℃		Density ρ	Flexural Strength
Material	Grade	T	kGs	kA/m	kOe	kA/m	kOe	kJ/m³	MGOe	α (Br)	β (Hcj)	g/cm³	MPa
SmFeN/Ferrite Hybrid Magnet	30A	0.37	3.70	213	2.67	336	4.22	25.5	3.20	-0.13	-0.35	3.61	98
	40A	0.45	4.50	220	2.76	398	5.00	32.4	4.07	-0.09	-0.48	3.70	91
	50A	0.48	4.80	270	3.39	423	5.32	40.6	5.10	-0.08	-0.48	3.79	89
SmFeN Magnet	60A	0.52	5.20	349	4.39	576	7.23	50.3	6.32	-0.07	-0.48	3.62	92
	70A	0.57	5.70	363	4.57	554	6.96	57.9	7.27	-0.08	-0.48	3.88	91
	80A	0.60	6.00	371	4.66	525	6.60	64.7	8.13	-0.08	-0.48	4.11	91
	90A	0.64	6.40	400	5.02	550	6.91	75.2	9.45	-0.08	-0.48	4.33	88
SmFeN/NdFeB Hybrid Magnet	100A	0.69	6.90	408	5.12	701	8.81	82.0	10.30	-0.10	-0.57	4.45	99
SmFeN/NdFeB Hybrid Magnet	120A	0.78	7.80	454	5.70	812	10.20	99.3	12.47	-0.10	-0.57	4.95	91
The above-mentioned data of magnetic properties and physical properties are given at room temperature. The max working temperature of magnet is changeable due to length-diameter ratio and other environment factors.