Fe-based amorphous alloy composition for low heat treatment temperature
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Solution Overview
Problem
Existing Fe-based amorphous alloys for powder cores and coil encapsulated powder cores face challenges in achieving low glass transition temperatures, high conversion vitrification temperatures, good magnetization, and corrosion resistance, which are essential for optimal heat treatment temperatures and reduced core losses in high-frequency applications.
Innovation Solution
An Fe-based amorphous alloy composition of Fe 100-a-b-c-x-y-z-t Ni a Sn b Cr c P x C y B z Si t, where specific atomic fractions of elements are optimized to achieve a glass transition temperature of 740K or less and a high conversion vitrification temperature, with Ni and Cr additions to enhance magnetization and corrosion resistance while minimizing Sn content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the glass transition temperature (Tg) of the Fe-based amorphous alloy is decreased to achieve low optimum heat treatment temperature, then the optimum heat treatment temperature is reduced, but it becomes difficult to maintain high conversion vitrification temperature (Tg/Tm), good magnetization, and corrosion resistance simultaneously
Solution Approach 1:
The invention changes the chemical composition parameters of the Fe-based amorphous alloy by adding specific amounts of Ni (0-10 at%), Cr (1-6 at%), and controlling P (6.8-10.8 at%), C (2.2-9.8 at%), B (0-4.2 at%), and Si (0-3.9 at%). This parameter optimization achieves Tg≤740K while maintaining Tg/Tm≥0.52, high saturation magnetization (1.20-1.45 T), and excellent corrosion resistance through Cr addition
Solution Approach 2:
The invention creates a composite amorphous alloy system combining Fe with multiple alloying elements (Ni, Cr, P, C, B, Si) that work synergistically. Ni decreases Tg, Cr improves corrosion resistance and maintains magnetization, P and C control Tm to increase Tg/Tm, while B and Si enhance amorphous formability. This composite approach resolves the contradiction between low Tg and high reliability
2Temperature
If the glass transition temperature (Tg) is decreased to achieve low optimum heat treatment temperature, then heat treatment temperature is reduced, but conversion vitrification temperature (Tg/Tm) tends to decrease
Solution Approach 1:
The invention optimizes composition parameters to achieve Tg≤740K while maintaining Tg/Tm≥0.52. This is accomplished by controlling the melting point (Tm) through P (6.8-10.8 at%) and C (2.2-9.8 at%) additions, which lower Tm, thereby increasing the Tg/Tm ratio even as Tg is reduced. The synergistic effect of multiple elements maintains the stability of Tg/Tm
Solution Approach 2:
The alloying elements serve multiple functions simultaneously: Ni decreases Tg while maintaining Tg/Tm, Cr improves corrosion resistance without significantly affecting Tg/Tm, P and C control Tm to increase Tg/Tm ratio, and B/Si enhance amorphous formability. This multi-functionality resolves the contradiction between low Tg and high Tg/Tm
3Reliability
If Cr is added to improve corrosion resistance, then corrosion resistance is enhanced, but magnetization tends to decrease
Solution Approach 1:
The invention optimizes Cr content to 1-6 at%, which provides sufficient corrosion resistance while limiting the negative impact on magnetization. Simultaneously, Ni (0-10 at%) is added to compensate for magnetization loss and enhance saturation magnetization. The synergistic combination of Cr and Ni achieves both high corrosion resistance and high magnetization
4Temperature
If Ni is added to decrease glass transition temperature (Tg), then Tg is reduced, but conversion vitrification temperature (Tg/Tm) may decrease
Solution Approach 1:
The invention controls Ni content at 0-10 at% to decrease Tg while maintaining Tg/Tm≥0.52. This is achieved by compensating for Tm reduction through P (6.8-10.8 at%) and C (2.2-9.8 at%) additions, which lower Tm and thereby maintain the Tg/Tm ratio even as Tg decreases due to Ni addition
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 alloy composition effectively decreases the optimum heat treatment temperature, increases inductance, and reduces core loss, leading to improved power supply efficiency and high magnetization with enhanced corrosion resistance.
Implementation Method 1
a heat treatment is performed on a powder core formed to have a targeted shape from an Fe-based amorphous alloy with a binding agent in order to reduce stress deformation generated when a powder of the Fe-based amorphous alloy is formed and/or stress deformation generated when the powder core is formed
Implementation Method 2
a glass transition temperature (Tg) of the Fe-based amorphous alloy was necessarily decreased
Data Source
Figure 1~2(a)
Figure 2(b)~3
Figure 4~5
AI summary
[Object] An object is to provide an Fe-based amorphous alloy used for a powder core and/or a coil encapsulated powder core having, in particular, a low glass transition temperature (Tg), a high conversion vitrification temperature (Tg/Tm), and excellent magnetization and corrosion resistance. [Solution] An Fe-based amorphous alloy of the present invention has a composition formula represented by Fe100-a-b-c-x-y-z-tNiaSnbCrcPxCyBzSit, and in the formula, 0 at%≤a≤10 at%, 0 at %≤b≤3 at%, 0 at%≤c≤6 at%, 6.8 at%≤x≤10.8 at%, 2.2 at%≤y≤9.8 at%, 0 at%≤z≤4.2 at%, and 0 at%≤t≤3.9 at% hold. Accordingly, an Fe-based amorphous alloy used for a powder core and/or a coil encapsulated powder core having a low glass transition temperature (Tg), a high conversion vitrification temperature (Tg/Tm), and excellent magnetization and corrosion resistance can be manufactured.