FeCo Laminated Core Alloy With Controlled Phase-Transition Annealing
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Solution Overview
Problem
Existing soft magnetic materials like SiFe and CoFe alloys are costly and require complex manufacturing processes, limiting their efficiency and power density in applications such as electric machines, while commercially available CoFe alloys have high cobalt content and high material and manufacturing costs.
Innovation Solution
A soft magnetic FeCo alloy with controlled composition and heat treatment process, including specific phase transition temperatures and controlled heating and cooling rates, to produce a precursor that maintains planarity and enhances magnetic properties, reducing cobalt content and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If commercially available CoFe alloys with high cobalt content (49 wt% Co) are used, then saturation induction and electrical resistance are improved, but material costs and manufacturing costs increase significantly
Solution Approach 1:
The patent changes the compositional parameters by reducing cobalt content from 49 wt% to 10-35 wt% and adjusting alloying elements (V: 0.5-5 wt%, Cr: 0.5-3 wt%, Si: 0.1-3 wt%) to achieve the desired magnetic properties at lower cost while maintaining high saturation induction and electrical resistance
Solution Approach 2:
The patent creates a composite alloy system Fe-Co-V-Cr-Si that combines multiple elements in specific proportions to achieve the desired magnetic properties, replacing the simple binary CoFe alloy with a multi-element composite that provides enhanced performance at reduced cost
2Reliability
If high cobalt content (49 wt% Co) is used to achieve high saturation induction, then magnetic performance is improved, but manufacturing complexity and additional manufacturing steps increase
Solution Approach 1:
The patent simplifies the manufacturing process by adjusting compositional parameters to enable direct casting and rolling without intermediate quenching steps, reducing process complexity while maintaining high magnetic performance through optimized alloy composition
3Productivity
If rapid heating and cooling rates are used during heat treatment, then processing time is reduced, but sheet planarity is lost and wavy deformation occurs
Solution Approach 1:
The patent utilizes controlled phase transitions during heat treatment, heating through the BCC-FCC transformation range at rates of 1-100 K/h to achieve planar sheets with fine-grained equiaxed microstructure, where the controlled phase transition prevents thermal stress and deformation while maintaining productivity
4Ease of manufacture
If cobalt content is reduced to lower material costs, then manufacturing cost is improved, but magnetic properties (permeability and induction) deteriorate
Solution Approach 1:
The patent compensates for reduced cobalt content by creating a multi-element composite alloy Fe-Co-V-Cr-Si where vanadium, chromium, and silicon work synergistically to maintain high permeability (>5000) and induction (>1.9 T) even with only 10-35 wt% cobalt, achieving cost reduction without magnetic property deterioration
Solution Approach 2:
The patent optimizes the parameters of multiple alloying elements simultaneously (Co: 10-35 wt%, V: 0.5-5 wt%, Cr: 0.5-3 wt%, Si: 0.1-3 wt%) to achieve the desired magnetic properties at lower cobalt content, using parameter optimization to maintain performance while reducing cost
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 FeCo alloy achieves higher permeability, lower hysteresis losses, and improved induction, reducing material and manufacturing costs, enabling higher power density and performance in electric machines.
Implementation Method 1
The precursor exhibits a phase transition from a BCC phase region to a BCC/FCC mixed region to an FCC phase region, wherein, with increasing temperature, the phase transition between the BCC phase region and the BCC/FCC mixed region takes place at a first transition temperature TÜ1 and, with further increasing temperature, the transition between the BCC/FCC mixed region and the FCC phase region takes place at a second transition temperature TÜ2
Implementation Method 2
The pre-product undergoes the following heat treatment, whereby before the start of the heat treatment the pre-product has a cold-rolled texture or a fiber texture: Heating the precursor to a temperature T1, then heat-treating the precursor at temperature T1 for a duration t1, and then cooling from T1 to room temperature
Data Source
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Figure 3~4
AI summary
A soft magnetic alloy is provided, consisting essentially of 5 wt.% ≤ Co ≤ 25 wt.%, 0.3 wt.% ≤ V ≤ 5.0 wt.%, 0 wt.% ≤ Cr ≤ 3.0 wt.%, 0 wt.% ≤ Si ≤ 3.0 wt.%, 0 wt.% ≤ Mn ≤ 3.0 wt.%, 0 wt.% ≤ Al ≤ 3.0 wt.%, 0 wt.% ≤ Ta ≤ 0.5 wt.%, 0 wt.% ≤ Ni ≤ 0.5 wt.%, 0 wt.% ≤ Mo ≤ 0.5 wt.%, 0 wt.% ≤ Cu ≤ 0.2 wt.%, 0 wt.% ≤ Nb ≤ 0.25 wt.%, and up to Contains 0.2 wt% impurities.