LaFeSi Alloy Plasma Spheroidization for Magnetic Refrigeration
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Solution Overview
Problem
The production of La(Fe, Si)13 phase-based magnetic refrigeration material particles faces challenges due to high-temperature, long-duration heat treatment requirements and variability in composition and properties when using conventional methods, leading to inefficient generation of the La(Fe, Si)13 phase and poor practical utility, especially when attempting to fabricate spherical particles.
Innovation Solution
An alloy composition with specific ranges of La, Fe, Si, and optional elements like B or Ti is used, which is partially melted by plasma, separated into small pieces, spheroidized, and then heat-treated to produce spherical particles with a uniform phase structure and improved magnetocaloric properties, reducing composition variations and enhancing the generation efficiency of the La(Fe, Si)13 phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional arc melting or high-frequency melting method is used to produce La(Fe, Si)13 phase, then the phase can be formed through heat treatment, but the process requires high temperature (900-1100°C) and long duration (several days to several months) heat treatment
Solution Approach 1:
The patent applies preliminary action by adding specific elements (B, C, or N) to the alloy composition before melting. These elements prepare the system in advance to enable rapid formation of La(Fe, Si)13 phase during subsequent heat treatment, eliminating the need for long-duration processing while ensuring reliable phase formation.
2Ease of manufacture
If conventional melting method is used, then the alloy can be produced, but coarse crystal phases with intricate metallographic structure are formed requiring long heat treatment
Solution Approach 1:
The patent applies local quality by introducing specific elements (B, C, or N) at controlled concentrations (0.1-5.0 atomic %) into the alloy system. These elements locally modify the crystallization behavior and phase formation kinetics, enabling fine-grained uniform microstructure to develop during heat treatment without requiring complex processing conditions.
3Loss of time
If ribbon-like magnetic refrigeration material is produced by liquid quenching method, then long-term heat treatment can be eliminated, but the material has poor practical utility for spherical particle fabrication
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the alloy system through addition of B, C, or N elements. This compositional modification changes the physical properties and phase formation characteristics, enabling the material to be processed into spherical particles with appropriate mechanical properties while maintaining rapid phase formation capability that eliminates long heat treatment.
4Reliability
If La(Fe, Si)13 based substance is used for magnetic refrigeration, then large magnetic entropy change is achieved in low magnetic field, but composition variations lead to property variations among particles
Solution Approach 1:
The patent applies homogeneity by incorporating B, C, or N elements into the alloy composition that promote uniform phase formation and distribution. These elements act as micro-alloying additives that enhance compositional uniformity during solidification and heat treatment, ensuring consistent La(Fe, Si)13 phase formation across all particles while maintaining the desired magnetocaloric properties.
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 allows for the efficient production of magnetic refrigeration material particles with uniform properties and improved magnetocaloric performance, reducing the variability in Curie temperature and enhancing the refrigerating effect in the AMR method.
Implementation Method 1
melting partially with plasma the alloy material according to the invention
Implementation Method 2
spheroidizing the melted alloy separated into the small pieces by the surface tension in an atmosphere
Implementation Method 3
produce gradually La(Fe, Si)13 phase by interdiffusion of the elements
Implementation Method 4
the integrated alloy is subjected to a heat treatment at a temperature of about 900 to 1100° C. for a long period of time
Implementation Method 5
When a magnetic field applied to a certain type of magnetic substance is changed in an adiabatic state, its temperature is changed. This phenomenon is called a magnetocaloric effect.
Implementation Method 6
changed in an adiabatic state, its temperature is changed
Data Source
AI summary
An alloy is used for production of magnetic refrigeration material particles. The alloy contains La in a range of 4 to 15 atomic %, Fe in a range of 60 to 93 atomic %, Si in a range of 3.5 to 23.5 atomic % and at lease one element M selected from B and Ti in a range of 0.5 to 1.5 atomic %. The alloy includes a main phase containing Fe as a main component element and Si, and a subphase containing La as a main component element and Si. The main phase has a bcc crystal structure and an average grain diameter of 20 μm or less.