Method for preparing gamma'-Fe4N soft magnetic material by utilizing liquid nitrogen via high-speed ball milling

Abstract

The invention discloses a method for preparing a gamma'-Fe4N soft magnetic material by utilizing liquid nitrogen via high-speed ball milling, and belongs to the field of soft magnetic materials. According to the method, high-energy low-temperature grinding in the liquid nitrogen is utilized to obtain a nano material FexN with a nitrogen atom supersaturation degree; and at low temperature, the material is crispy and the surface volume ratio is very high, so that 22% of nitrogen atoms are adsorbed on the surface of a sample; after the temperature is up to 300 DEG C, annealing is carried out to ensure that alpha-Fe directly undergoes phase change to be converted to gamma'-Fe4N, so as to prepare a nanocrystal gamma'-Fe4N soft magnetic material. The method is simple to convenient to operate, low in cost and suitable for large-scale industrial production, and is a novel replacement method for preparing high-level soft magnetic materials with ideal magnetism. The gamma'-Fe4N soft magnetic material prepared by the method has the advantages of being high in Ms, low in coercive force and high surface resistivity, and can be applied to transformer and inductors operated in high-frequency semi-conductor switches.

Description

technical field [0001] The invention belongs to the field of soft magnetic materials, in particular to a method for preparing γ'-Fe by using liquid nitrogen high-speed ball milling 4 N method for soft magnetic materials. Background technique [0002] Since the early 1950s, people have studied iron nitride materials, initially to study the nitriding phenomenon on the surface of steel to improve the hardness and oxidation resistance of the steel surface. With the in-depth research on iron nitride materials, it has been found that iron nitride materials have excellent ferromagnetic properties, good wear resistance, corrosion resistance, and oxidation resistance, and are good high-density magnetic recording media and thin-film magnetic heads. candidate materials. So people began to study more deeply on iron nitride materials. Due to the different nitrogen content in iron nitride materials, iron nitride materials have different crystal structures, and there are many phases, esp...

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Problems solved by technology

[0003] However, γ'-Fe 4 The preparation of N is challenging, and most of the material preparation work so far has been based on the preparation of thin-film materials

There have been some reports on the preparation of granular materials, but the γ'-Fe 4 The purity of N is relatively low, and most of it is mixed with other iron nitride phases or other undesirable forms and particle sizes. The method used generally uses ammonia as a nitrogen source to provide nitrogen atoms, and the nitrogen content of the obtained materials is generally 6%. around, not more than 10%, is low in γ'-Fe 4 A mixture of N, it is difficult to achieve a pure phase, which seriously affects the γ'-Fe 4 Excellent soft magnetic properties of N

According to γ'-Fe 4 According to the requirements of the atomic ratio of N, the content of nitrogen atoms should be about 20%, but the solid solubility of nitrogen atoms in iron is only 11.7%, so according to the conventional nitrogen doping method, only about 50% of the purity can be obtained at most. γ'-Fe 4 N, therefore, the main obstacle to the preparation of this material is the content of nitrogen atoms, how to overcome the solid solubility of nitrogen atoms in iron, so as to improve the γ'-Fe 4 The purity of N is the bottleneck in the preparation of this material

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