Fe-Co Magnetic Wire Microstructure for Stable Miniature Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic wires used in magnetic sensors exhibit large Barkhausen jumps, limiting their performance and miniaturization potential.
Innovation Solution
A magnetic wire composed of an alloy with a specific structure containing α and γ phases, high angle grain boundaries, and controlled proportions and sizes, which is twisted to introduce tensile residual stress and enhance uniaxial anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional magnetic wires are used to achieve large Barkhausen jumps, then magnetic sensor output is sufficient, but device miniaturization is limited
Solution Approach 1:
The patent changes the microstructural parameters of the magnetic wire by controlling the α phase proportion (90-99%) and average crystal grain size (2.5 μm or less) through specific heat treatment processes. This enables miniaturization while maintaining reliable output characteristics by optimizing the balance between grain size and phase composition.
Solution Approach 2:
The patent creates a composite microstructure consisting of α phase and γ phase regions within the magnetic wire. This composite structure at the microscale allows the material to exhibit both high Barkhausen jump characteristics and stability, enabling miniaturized sensors to maintain reliable performance.
2Strength
If heat treatment and twisting are applied to improve magnetic wire structure, then uniaxial anisotropy increases, but manufacturing complexity increases
Solution Approach 1:
The patent applies heat treatment before the final twisting step to pre-establish the desired α phase proportion and crystal grain size. This preliminary action optimizes the microstructure in advance, allowing the subsequent twisting to focus solely on introducing tensile residual stress and enhancing uniaxial anisotropy without requiring additional complex processing steps.
Solution Approach 2:
The patent integrates heat treatment and twisting into a continuous manufacturing sequence where the heat-treated wire is immediately twisted while maintaining structural integrity. This continuous process eliminates intermediate handling steps and maintains the beneficial microstructural state established during heat treatment, simplifying the overall manufacturing process.
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 magnetic wire achieves high output characteristics with reduced output variation, enabling miniaturization of magnetic sensors.
Implementation Method 1
When a certain external magnetic field is applied, the above magnetic wire causes a rapid magnetic reversal regardless of the change rate of the external magnetic field. A pulse voltage is generated on the above coil by electromagnetic induction accompanied with the rapid magnetic reversal.
Implementation Method 2
A magnetic wire that may cause a large Barkhausen jump phenomenon has conventionally been utilized in a magnetic sensor. When a certain external magnetic field is applied, the above magnetic wire causes a rapid magnetic reversal regardless of the change rate of the external magnetic field.
Data Source
AI summary
A magnetic wire made of an alloy containing iron and cobalt as main components, wherein the magnetic wire has a structure including at least an α phase of the α phase and a γ phase, the structure has a high angle grain boundary having a misorientation of 15° or more, the proportion of the area of the α phase relative to the total area of the α phase and the γ phase in a cross section of the magnetic wire is 90% or more, the average crystal grain size of the α phase in the cross section is 2.5 μm or less, and the proportion of the length of the high angle grain boundary relative to the total length of grain boundaries in the structure in the cross section is 60% or more.