Dual-Phase Magnetic Component via Selective Nitrogen Diffusion
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Solution Overview
Problem
Current electric machines for hybrid and electric vehicles face a tradeoff between power density, efficiency, and rotor mechanical strength, with traditional methods of increasing magnetic utilization being limited by the presence of carbides which increase coercivity and reduce magnetic saturation.
Innovation Solution
A method of forming a dual-phase magnetic component by selectively expelling nitrogen from a non-magnetic austenite composition to create regions of high and low permeability, using a masking process to control nitrogen diffusion and maintain the austenite phase in non-magnetic regions, thereby reducing coercivity and enhancing magnetic saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If carbides are present in the magnetic microstructure to stabilize austenite regions, then the austenite phase can be maintained at room temperature, but coercivity increases and magnetic saturation decreases
Solution Approach 1:
The patent removes carbides from the magnetic microstructure by using a nitrogen-containing alloy composition and controlled heat treatment. The nitrogen stabilizes the austenite phase without requiring carbide formation, thereby extracting the harmful carbide phase while maintaining austenite stability at room temperature, which reduces coercivity and improves magnetic saturation.
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating nitrogen (0.01-2.00 wt%) into the alloy, which fundamentally alters the phase stability mechanism. Instead of relying on carbide formation, nitrogen directly stabilizes the austenite phase through solid solution strengthening and electronic effects, enabling room temperature austenite without the detrimental effects of carbides on magnetic properties.
2Power
If the machine size is increased to increase power density, then power density improves, but the machine mass and cost increase
Solution Approach 1:
The patent changes the magnetic material properties by creating a dual-phase microstructure with regions of different permeability. This increases the magnetic utilization factor, allowing the machine to generate more power per unit volume without increasing size, thereby improving power density while avoiding increased mass.
Solution Approach 2:
The patent creates a composite magnetic microstructure consisting of austenite regions (high permeability) and ferrite/martensite regions (low permeability). This dual-phase composite material optimizes both magnetic flux conduction and mechanical strength, enabling higher power density in a compact machine design.
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 allows for the creation of high-power density electric machines with improved efficiency by stabilizing austenite regions at room temperature, reducing coercivity, and increasing magnetic saturation, thus overcoming the limitations of traditional methods.
Implementation Method 1
heating the initial component to a treatment temperature such that nitrogen diffuses out of the unmasked area of the initial component
Implementation Method 2
forming a coating on a portion of the surface of the initial component to form a masked area while leaving an unmasked area thereon
Data Source
AI summary
Methods for forming a dual-phase magnetic component from an initial component comprising a non-magnetic austenite composition are provided. The method may include: forming a coating on a portion of the surface of the initial component to form a masked area while leaving an unmasked area thereon. Thereafter the initial component may be heated to a treatment temperature such that nitrogen diffuses out of the unmasked area of the initial component to transform the non-magnetic austenite composition to a magnetic phase in the unmasked area. Thereafter, the initial component may be cooled from the treatment temperature to form a dual-phase magnetic component having a magnetic region corresponding to the unmasked area and a non-magnetic region corresponding to the masked area.