Fe-based Soft Magnetic Thin Strip with Fine Crystalline Grains
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Solution Overview
Problem
Current soft magnetic materials face challenges such as high core loss in high-frequency applications, low saturation magnetic flux density, thermal instability, and high cost due to Co content, along with issues like high noise and magnetostriction, which limit their effectiveness in high-power applications.
Innovation Solution
A soft magnetic thin ribbon with a composition of Fe-based alloy containing elements like Cu, Ti, Zr, and P, produced through rapid cooling and high-temperature annealing, resulting in fine crystalline grains dispersed in an amorphous phase, achieving a saturation magnetic flux density of not lower than 1.7 T and low coercive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Fe-based amorphous soft magnetic alloy is used, then soft magnetic properties are improved, but saturation magnetic flux density is limited to about 1.65 T
Solution Approach 1:
The invention changes the fundamental structural parameter from amorphous to fine crystalline with grain size of 10 nm to 100 nm. This parameter change enables the material to achieve saturation magnetic flux density of 1.7 T or higher while maintaining excellent soft magnetic properties, overcoming the 1.65 T limit of conventional amorphous alloys
Solution Approach 2:
The invention creates a composite structure consisting of fine crystalline grains dispersed in an amorphous matrix. This composite architecture combines the advantages of both crystalline (high saturation flux density) and amorphous (excellent soft magnetic properties) phases, achieving performance that neither phase can provide alone
2Reliability
If Fe-based amorphous soft magnetic alloy is used, then coercive force is reduced, but magnetostriction increases causing high noise
Solution Approach 1:
The invention changes the grain size parameter to the nano-scale range (10-100 nm), which fundamentally alters the magnetic domain structure. This enables the material to exhibit both low coercive force and low magnetostriction, eliminating the trade-off present in conventional materials
Solution Approach 2:
The invention creates local crystalline regions with specific grain size characteristics within the amorphous matrix. These localized fine crystalline structures provide low magnetostriction properties while the overall composite structure maintains low coercive force, resolving the contradiction between these two properties
3Quantity of substance
If Co-based amorphous alloy is used, then saturation magnetic flux density is achieved, but thermal instability occurs
Solution Approach 1:
The invention replaces expensive and thermally unstable Co-based amorphous alloys with a Fe-based fine crystalline alloy. The Fe-based composition is inherently more thermally stable and cost-effective, while the fine crystalline structure maintains high saturation magnetic flux density of 1.7 T or higher
Solution Approach 2:
The fine crystalline-amorphous composite structure provides thermal stability through the amorphous matrix while the dispersed fine crystalline grains maintain high magnetic performance. This composite approach eliminates the thermal instability inherent in Co-based amorphous alloys
4Quantity of substance
If silicon steel plate is used, then magnetic flux density is high, but core loss increases in high-frequency applications
Solution Approach 1:
The invention changes the material structure from conventional crystalline silicon steel to fine crystalline with 10-100 nm grain size. This dramatic reduction in grain size reduces eddy current paths and magnetic domain wall movement losses, thereby reducing core loss in high-frequency applications while maintaining high magnetic flux density
Solution Approach 2:
The fine crystalline structure with grain sizes in the 10-100 nm range creates a microstructure that effectively reduces eddy currents. The thin crystalline regions act as natural insulation barriers, reducing energy loss in high-frequency applications compared to conventional thick-grained silicon steel
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective, high-performance soft magnetic material with improved toughness, low hysteresis loss, and reduced noise, suitable for high-power applications, including transformers, reactors, and noise suppression parts.
Implementation Method 1
produced through rapid cooling and high-temperature annealing
Implementation Method 2
resulting in fine crystalline grains dispersed in an amorphous phase
Implementation Method 3
produced through rapid cooling and high-temperature annealing
Implementation Method 4
resulting in fine crystalline grains dispersed in an amorphous phase
Data Source
AI summary
The invention provides a soft magnetic thin strip which contains nanoscale fine grains and exhibits a high saturation magnetic flux density and excellent soft magnetic characteristics; a process for production of the same; magnetic parts; and an amorphous thin strip to be used in the production. In the invention, an amorphous thin strip is used, which is represented by the composition formula: Fe100-x-y-zAxMyXz-aPa (wherein A is at least one element selected from between Cu and Au; M is at least one element selected from among Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Mn; X is at least one element selected from between B and Si; and x, y, z and a (in terms of atomic percentage) satisfy the relationships: 0.5 ≦ x ≦ 1.5, 0 ≦ y ≦ 2.5, 10 ≦ z ≦ 23, and 0.35 ≦ a ≦ 10 respectively) and permits 180° bending. The amorphous thin strip can give through anneal a soft magnetic thin strip having a structure wherein grains of body-centered cubic structure having an average grain size of 60nm or below are distributed in an amorphous phase with a grain volume fraction of 30% or above.