Fe-Based Soft Magnetic Alloy Undercooling for High Magnetization
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Solution Overview
Problem
The challenge in preparing Fe-based amorphous or nanocrystalline soft magnetic alloys is the limited saturation magnetization due to the requirement for a high proportion of non-magnetic elements to promote amorphous formation, which restricts the content of ferromagnetic elements and hinders the development of high-power and miniaturized soft magnetic devices.
Innovation Solution
The method involves undercooling solidification using glass fluxing combined with cyclical superheating or electromagnetic levitation melting to reduce the additive amount of non-magnetic elements, increasing the Fe content and enhancing saturation magnetization while maintaining low coercive force, by optimizing the alloy composition and processing conditions to achieve high Fe content in the amorphous or nanocrystalline structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-magnetic elements are added to promote amorphous formation, then amorphous structure formation is improved, but saturation magnetization decreases
Solution Approach 1:
The patent applies parameter changes by dramatically increasing the cooling rate from conventional rates to exceed 10^5 °C/s through electromagnetic induction melting and rapid quenching. This parameter change in cooling rate allows the alloy to form amorphous structure with much lower content of non-magnetic elements (Si: 1-5 at%, B: 2-10 at%) compared to conventional alloys, thereby achieving high saturation magnetization (1.75-1.85 T) while maintaining amorphous formation
Solution Approach 2:
The patent creates a composite alloy system Fe-Si-B with specific composition ratios where Fe content is optimized at 85-90 at%, Si at 1-5 at%, and B at 2-10 at%. This composite material design allows the synergistic effect of Fe providing high magnetization and Si-B providing amorphous formation capability, achieving both high saturation magnetization and low coercive force in the same material system
2Quantity of substance
If Fe content is increased to improve saturation magnetization, then saturation magnetization is improved, but amorphous formation ability deteriorates
Solution Approach 1:
The patent overcomes the limitation of high Fe content on amorphous formation by changing the cooling rate parameter to exceed 10^5 °C/s. This extreme cooling rate suppresses crystal nucleation and growth kinetics, allowing even high Fe content alloys (85-90 at% Fe) to form amorphous structures. The rapid quenching process prevents the Fe atoms from arranging into crystalline structures, thereby maintaining amorphous formation ability while achieving high saturation magnetization
3Reliability
If cooling rate is increased to achieve amorphous structure, then amorphous structure formation is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces conventional mechanical cooling methods with electromagnetic induction melting followed by rapid quenching in a water-cooled copper mold. The electromagnetic induction heating provides extremely rapid and uniform heating, while the water-cooled copper mold provides instantaneous cooling. This substitution of mechanical cooling with electromagnetic processing achieves the required cooling rate (>10^5 °C/s) with better process control and reduced manufacturing complexity
Solution Approach 2:
The patent utilizes phase transition phenomena by melting the alloy through electromagnetic induction and then rapidly quenching it through phase transition from liquid to amorphous solid state. The water-cooled copper mold facilitates this phase transition by providing extreme cooling rates, causing the molten alloy to solidify into amorphous structure without passing through crystalline phases. This phase transition approach simplifies the manufacturing process while ensuring amorphous structure formation
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
This approach effectively increases the saturation magnetization and reduces coercive force in Fe-based amorphous or nanocrystalline alloys, broadening the composition design range and improving the magnetic properties, thereby enhancing the performance of soft magnetic devices.
Implementation Method 1
electromagnetic levitation melting
Implementation Method 2
undercooling solidification
Implementation Method 3
solidifying the undercooled and solidified alloy into strips or powders through rapid quenching
Implementation Method 4
carrying out crystallization annealing to obtain a Fe-based nanocrystalline alloy
Implementation Method 5
carrying out stress-relief annealing to obtain a Fe-based amorphous alloy
Data Source
AI summary
The present invention provides an undercooling solidification method for preparing an amorphous or nanocrystalline soft magnetic alloy with high Fe content and the applicable amorphous or nanocrystalline alloy composition. The undercooling solidification is realized by glass purification combined with cyclical superheating or electromagnetic levitation melting. An undercooling solidification alloy is prepared into amorphous strips or powders through rapid quenching or atomization of melt, and can be prepared into a nanocrystalline alloy through heat treatment. The chemical formula of the applicable amorphous or nanocrystalline alloy is FeSiBM, wherein M is one or more of P, C, Nb, Mo, Zr, Hf, Mo, Y, Cu and Co. The amorphous or nanocrystalline alloy prepared by undercooling non-equilibrium solidification has the characteristics of high amorphous forming ability, high saturation magnetization and low coercive force.