Magnetism of intermetallic nitrides: a review

A brief review of recent work dealing with nitrides of selected intermetallic compounds is presented. Emphasis is on those systems which are of potential significance for high-energy permanent magnet fabrication. Of the many nitrogenated intermetallics that have been studied, only Sm₂Fe₁₇N_x and NdTiFe₁₁N_x seem promising for permanent magnet fabrication. Nitrides of the 2:17 intermetallics show that only the Sm compound has appropriate properties. This is unfortunate because of the scarcity and high cost of Sm. This can be alleviated partially by replacing a portion of Sm with Mischmetal. Considerable replacement can be effected with only slight loss of the desirable properties. It is further pointed out that conventional powder metallurgical techniques are unsuitable for magnet fabrication using the nitrides because these compounds decompose at sintering temperatures. Bonded magnets using Zn as the bonding agent lead to 10 MGOe magnets