Soft magnetic materials and methods of making

Abstract

An article including a monolithic body including iron, cobalt, and nitrogen is provided. The monolithic body includes a matrix phase and a plurality of particles disposed within the matrix phase. The particles include a phase comprising nitrogen.

Description

BACKGROUND OF THE INVENTION [0001] The invention is related to a soft magnetic material. More particularly, the invention is related to a soft magnetic material comprising iron, cobalt, and nitrogen. The invention is also related to a method for making a soft magnetic material. [0002] Soft magnetic materials play a key role in a number of applications, especially in electric and electromagnetic devices. There is a growing need for lightweight, and compact electric generators. Compact machine designs may be realized through an increase in the rotational speed of the machine. In order to operate at very high speeds, these machines need rotors with higher yield strength materials along with lower magnetic core losses, as well as the ability to operate at maximum flux densities. Generally, achieving high strength and superior magnetic performance concurrently is difficult in conventional materials, because high strength typically is obtained at the expense of magnetic properties such as...

AI Technical Summary

Benefits of technology

[0008] For many applications, magnetic materials with high permeability, high saturation magnetization, low core loss, and high mechanical strength are preferred. Therefore, there is a continuing need for magnetic materials with improved magnetic properties and mechanical strength.

[0011] In one embodiment, cobalt is present in the monolithic body in the range from about 15 atomic percent to about 55 atomic percent. In another embodiment, the monolithic body comprises cobalt in the range from about 30 atomic percent to about 40 atomic percent. In one embodiment, the monolithic body comprises Co in the range from about 45 atomic percent to about 52 atomic percent. The amount of cobalt may be chosen to optimize the mechanical processability and the magnetic properties of the alloy. Nitrogen in the form of nitrides and interstitial nitrogen in Fe—Co soft magnetic material is expected to increase the yield strength and increase the resistivity. The bulk resistivity and hence the eddy current loss of the magnetic structure can be controlled by controlling the amount of nitrogen introduced. In one embodiment, the monolithic body comprises nitrogen in an amount less than about 6 atomic percent. In one embodiment, the monolithic body comprises nitrogen in the range from about 0.05 atomic percent to about 2 atomic percent. In another embodiment, the monolithic body phase comprises nitrogen in the range from about 0.5 atomic percent to about 1 atomic percent. The amount of nitrogen may be optimized to obtain desired mechanical and electrical properties. The alloys of the invention desirably exhibit high saturation magnetization Bs and high Curie temperatures Tc (Tc≈900° C.). In one embodiment, magnetic material of the invention has a saturation magnetization of at least about 1.8 T. In another embodiment, magnetic material of the invention has a saturation magnetization at least about 2 T. The high saturation magnetization values allow the material to be operated at very high flux densities, enabling compact electric machine designs, and the high Curie temperature enables the machine to operate at elevated temperatures.

Problems solved by technology

Generally, achieving high strength and superior magnetic performance concurrently is difficult in conventional materials, because high strength typically is obtained at the expense of magnetic properties such as magnetic saturation and core loss.