Nb3Sn Superconducting Wire Cu-Zn Alloy Matrix
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Solution Overview
Problem
The internal tin process for producing Nb3Sn superconducting wires faces challenges with large vacancies in the Cu matrix, impairing mechanical properties, and the bronze process has limitations in increasing the volume of Nb3Sn and critical current density due to processing hardening and Sn solid solution ratios.
Innovation Solution
A method involving a Cu-xZn-yM alloy matrix with Sn and Nb insertion holes, where M can be Ge, Ga, Mg, or Al, promoting mutual diffusion and heat treatment to form a dense Nb3Sn phase without significant vacancies, enhancing mechanical strength and critical temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the internal tin process is used to increase the volume of Nb3Sn and critical current density, then the Sn content can be increased beyond the bronze process limit, but large vacancies occur after Sn diffuses in the Cu matrix, impairing mechanical properties
Solution Approach 1:
The patent changes the matrix material composition from pure Cu to Cu-Zn alloy, specifically controlling Zn content at 1-30 mass%. This parameter change prevents vacancy formation during Sn diffusion while enabling high Nb3Sn volume fraction, thus resolving the contradiction between increasing Nb3Sn quantity and maintaining mechanical strength
Solution Approach 2:
The patent creates a composite structure with Cu-Zn alloy matrix containing embedded Nb cores and Sn. This composite approach allows the matrix to provide both the diffusion pathway for Sn and the mechanical strength support, preventing the vacancy-related mechanical degradation that occurs in pure Cu matrices
2Ease of manufacture
If the bronze process is used with Cu-Sn matrix, then the wire can be processed with good ductility, but the solid solution ratio of Sn is limited to ≤15.5 mass% and processing hardening occurs during wiredrawing
Solution Approach 1:
The patent changes the matrix composition from Cu-Sn to Cu-Zn alloy, removing Sn from the matrix and placing it only in insertion holes. This allows Sn content to exceed 15.5 mass% in the final wire while the Cu-Zn matrix maintains good processability during wiredrawing without processing hardening
3Reliability
If Sn is increased in the Cu matrix to enhance critical current density, then the Nb3Sn volume increases, but large vacancies form after Sn diffusion, impairing mechanical properties
Solution Approach 1:
The patent changes the matrix material from Cu to Cu-Zn alloy with controlled Zn content (1-30 mass%). This parameter change enables high Sn content (0.5-10 mass% in matrix) for enhanced critical current density while the Zn addition prevents vacancy formation, maintaining mechanical strength
Solution Approach 2:
The Cu-Zn alloy matrix acts as an intermediary that facilitates Sn diffusion for high critical current density while simultaneously preventing vacancy formation. The Zn elements serve as intermediaries that fill or prevent vacancy sites, decoupling the relationship between Sn content and mechanical degradation
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 method produces a Nb3Sn wire with improved mechanical strength, critical temperature, and reduced grain size, eliminating voids and enhancing strain characteristics, making it suitable for high-field applications like nuclear fusion and MRI magnets.
Implementation Method 1
promoting mutual diffusion and heat treatment to form a dense Nb3Sn phase
Implementation Method 2
subjecting the composite multicore wire to Nb3Sn phase generation heat treatment at 650° C. to 800° C.
Implementation Method 3
subjecting the composite multicore wire to Nb3Sn phase generation heat treatment at 650° C. to 800° C.
Data Source
AI summary
In the production of an internal-tin-processed Nb3Sn superconducting wire, the present invention provides a Nb3Sn superconducting wire that is abundant in functionality, such as, the promotion of formation of a Nb3Sn layer, the mechanical strength of the superconducting filament (and an increase in interface resistance), the higher critical temperature (magnetic field), and the grain size reduction, and a method for producing it. A method for producing a Nb3Sn superconducting wire according to an embodiment of the present invention includes a step of providing a bar 10 that has a Sn insertion hole 12 provided in a central portion of the bar 10 and a plurality of Nb insertion holes 14 provided discretely along an outer peripheral surface of the Sn insertion hole 12, and that has an alloy composition being Cu-xZn-yM (x: 0.1 to 40 mass %, M=Ge, Ga, Mg, or Al, provided that, for Mg, x: 0 to 40 mass %), a step of mounting an alloy bar with an alloy composition of Sn-zQ (Q=Ti, Zr, or Hf) into the Sn insertion hole 12 and inserting Nb cores into the Nb insertion holes 14, a step of subjecting the bar 10 to diameter reduction processing to fabricate a Cu-xZn-yM/Nb/Sn-zQ composite multicore wire with a prescribed outer diameter, and a step of subjecting the composite multicore wire to Nb3Sn phase generation heat treatment.