Fe-Ga Alloy Single Crystal Manufacturing via Electric Discharge Machining
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Solution Overview
Problem
The high cost and limited application of super-magnetostrictive materials like Tb-Dy-Fe due to their rarity and brittleness, along with the low productivity and high cost of manufacturing single crystal magnetostrictive members, restrict their use in vibration power generation, where alignment of crystal orientation is crucial for optimal magnetostrictive properties.
Innovation Solution
A method involving unidirectional solidification of Fe-Ga alloy, followed by cutting into a strip shape and separating individual single crystals using electric discharge machining to align the crystal orientation, allowing for the production of high-performance magnetostrictive members at a lower cost without requiring complex facilities or precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If super-magnetostrictive material (Tb-Dy-Fe) is used to achieve high magnetostriction (>1000 ppm), then the magnetostrictive property is improved, but the material cost increases significantly and the material becomes extremely brittle and difficult to process
Solution Approach 1:
The patent replaces expensive super-magnetostrictive materials (Tb-Dy-Fe) with a cheaper alternative material (Fe-Ga based alloy) that can achieve sufficient magnetostrictive properties (100-300 ppm) for vibration power generation applications. This substitution principle resolves the contradiction by using a more economical material that meets the functional requirements without the extreme brittleness and processing difficulties of rare earth-based materials.
2Reliability
If single crystal manufacturing methods (Bridgman method, pulling method, zone melting method) are used to achieve aligned crystal orientation and high magnetostrictive property, then the magnetostrictive property is improved, but the productivity becomes extremely low
Solution Approach 1:
The patent changes the manufacturing parameters and process conditions to achieve a different microstructure (fine-grained polycrystal) that can be produced much faster than single crystal methods. By controlling solidification conditions and using rapid cooling, the patent achieves sufficient crystal orientation alignment at grain boundaries while dramatically improving productivity compared to traditional single crystal growth methods.
Solution Approach 2:
The patent divides the material into fine-grained structures where each grain can be relatively small but collectively provides sufficient orientation alignment. This segmentation approach allows parallel processing of multiple grains during solidification, greatly increasing productivity compared to growing a single large crystal, while still achieving the necessary magnetostrictive properties through statistical orientation distribution.
3Productivity
If powder metallurgy method or pressure sintering method is used to manufacture polycrystal members, then the productivity is improved, but special facilities and controlled environments are required which increases manufacturing cost
Solution Approach 1:
The patent extracts and eliminates the need for complex special facilities (atomization facilities, liquid rapid solidification facilities, pressure sintering facilities) by using a simplified melting and solidification process. The invention achieves polycrystal formation with sufficient orientation through basic melting and controlled cooling in conventional equipment, removing the requirement for expensive and complex specialized equipment while maintaining high productivity.
4Productivity
If polycrystal material is used instead of single crystal to improve productivity, then the manufacturing cost is reduced, but the magnetostrictive property becomes less than optimal due to inability to align all crystal orientations
Solution Approach 1:
The patent applies local quality control by ensuring that while individual grains may have varying orientations, the overall statistical distribution of grain orientations provides sufficient alignment in the direction of interest. By controlling the solidification process and grain growth conditions, the patent creates a polycrystal structure where the majority of grains contribute constructively to the magnetostrictive effect, achieving a balance between productivity and performance.
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 method enables the cost-effective manufacturing of high-performance, reliable, and versatile magnetostrictive members with aligned crystal orientation, enhancing their magnetostrictive properties and expanding their application in vibration power generation.
Implementation Method 1
a step of retaining an Fe-Ga alloy in a furnace heated to a melting temperature or more for a predetermined time and then extracting the melted alloy out of the furnace at a predetermined speed to unidirectionally solidify the melted alloy
Implementation Method 2
cutting the separated individual single crystal by using electric discharge machining in a state that orientation of the crystal is aligned in a direction of the magnetostriction of a magnetostrictor
Implementation Method 3
the magnetostriction appears largely in the specific orientation of the crystal. Therefore, it is preferred that the material of the single crystal is used in a state that the orientation in which the magnetostriction of the crystal becomes the maximum is aligned with the direction in which the magnetostriction of the magnetostrictive member is required
Data Source
Figure 1(I)~2(II)
Figure 3~5
AI summary
[Problem] The present invention aims for providing a magnetostrictive member with high performance, high reliability and high versatility. The magnetostrictive member is used in the vibration power generation as a power source for extracting electric energy from various vibrations. The member made of the single crystal is manufactured cheaper than the conventional manufacturing method. [Solution] The magnetostrictive member is formed by cutting a single crystal of Fe-Ga alloy by using electric discharge machining in a state that <100> orientation of the crystal of the Fe-Ga alloy is aligned in a direction in which magnetostriction of the magnetostrictive member is required.