Fe-Ni Alloy Foil Microstructure Control for Flatness Stability
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Solution Overview
Problem
The production of Fe—Ni alloy foil with a thickness of 50 μm or less is hindered by nonuniform residual stress, leading to edge waves, center waves, and warping, which conventional methods fail to adequately address.
Innovation Solution
The method involves producing an Fe—Ni alloy ingot using hot powder metallurgy to uniformly disperse vacancies, followed by rolling and optional annealing to achieve a positron annihilation lifetime (PAL) of 0.150 ns or more, thereby uniformizing residual stress and suppressing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of Fe—Ni alloy foil is reduced to 50 μm or less, then the foil becomes lighter and thinner for electronic equipment, but nonuniform residual stress causes edge waves, center waves, and warping
Solution Approach 1:
The patent applies strain relief annealing at specific temperature ranges (500-800°C for Fe-50Ni alloy, 600-900°C for Fe-40Ni alloy) to change the thermal parameters of the material. This heat treatment modifies the internal stress distribution and microstructure, transforming the material properties to eliminate nonuniform residual stress and prevent deformation in thin foils
Solution Approach 2:
The patent performs strain relief annealing as a preliminary treatment before final foil production to pre-establish uniform stress distribution. By addressing residual stress early in the manufacturing process through controlled heating and cooling, the foil is prepared in advance to maintain flatness during subsequent handling and application
2Ease of manufacture
If conventional rolling methods are used to produce thin Fe—Ni alloy foil, then production is simpler, but nonuniform deformation occurs leading to quality issues
Solution Approach 1:
The patent modifies the thermal parameters during rolling by implementing strain relief annealing at controlled temperatures. This changes the material's mechanical properties temporarily during processing, allowing uniform deformation behavior while maintaining the simplicity of the rolling operation itself
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 results in Fe—Ni alloy foil with reduced deformation, such as edge waves and warping, by transforming the microstructure from dislocations to vacancies, enhancing the foil's quality and usability in thin applications.
Implementation Method 1
The method involves producing an Fe—Ni alloy ingot using hot powder metallurgy to uniformly disperse vacancies
Implementation Method 2
followed by rolling and optional annealing to achieve a positron annihilation lifetime (PAL) of 0.150 ns or more, thereby uniformizing residual stress
Data Source
AI summary
The present invention has as its technical problem the suppression of edge waves, center waves, warping, and other deformation in ultrathick (thickness 50 μm or less) Fe—Ni alloy foil and has as its object to obtain Fe—Ni alloy foil suppressed in such deformation. The Fe—Ni alloy foil according to the present invention has a positron annihilation lifetime (PAL) of 0.150 ns or more. The amount of deformation (comprehensive evaluation of edge waves, center waves, warping, and other deformation) can be made smaller than a conventional product. To obtain a microstructure mainly comprised of vacancies for making the PAL 0.150 ns or more, HIP-processing is used for producing an alloy ingot (slab). The alloy ingot can be rolled and heat treated in accordance with conventional method to obtain an Fe—Ni alloy foil.