Copper Alloy Wire Rod with Silver Precipitates
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Solution Overview
Problem
Conventional copper alloy wire rods fail to simultaneously achieve high tensile strength, flexibility, conductivity, and bending fatigue resistance, particularly due to the trade-offs between these properties in existing manufacturing processes and compositions.
Innovation Solution
A copper alloy wire rod with a chemical composition of Ag 0.1 to 6.0 mass% and P 0 to 20 mass ppm, balanced with copper and inevitable impurities, featuring second phase particles with an aspect ratio greater than or equal to 1.5 and a size less than 200 nm, manufactured through controlled melting, casting, wire drawing, and heat treatment processes to enhance tensile strength, flexibility, and bending fatigue resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wire rods are work-hardened by wire drawing to improve tensile strength and bending fatigue resistance, then strength increases, but flexibility deteriorates
Solution Approach 1:
The invention changes the physical and chemical parameters of the copper alloy by controlling the size, shape, and distribution of second phase particles (silver-containing precipitates). By maintaining particle sizes of 100 nm or less and controlling their number density to 1.0 particles/μm² or more, the material achieves both high strength and high flexibility simultaneously, resolving the trade-off between work hardening and ductility.
Solution Approach 2:
The invention creates a composite microstructure consisting of a copper matrix with dispersed second phase particles (silver-containing precipitates). This composite structure provides reinforcement for strength while the fine particle distribution maintains ductility and flexibility, avoiding the brittleness associated with conventional work hardening.
2Ease of operation
If wire rods are heat-treated to improve flexibility, then flexibility increases, but tensile strength and bending fatigue resistance deteriorate
Solution Approach 1:
The invention uses controlled heat treatment to precipitate fine second phase particles (100 nm or less) from the copper matrix. This parameter change in the microstructure allows the material to achieve high flexibility through annealing while maintaining high strength through the reinforcing effect of the precipitated particles, reversing the conventional trade-off.
3Strength
If silver is added to copper to improve strength through precipitation strengthening, then tensile strength increases, but conductivity decreases
Solution Approach 1:
The invention applies local quality by concentrating the silver content into discrete second phase particles (100 nm or less) distributed throughout the copper matrix, rather than having silver uniformly dissolved in the matrix. This localized precipitation provides strength reinforcement at particle sites while maintaining high conductivity in the bulk copper matrix, as silver atoms are removed from the copper lattice where they would scatter electrons.
4Strength
If conventional precipitation strengthening is performed to compensate for strength reduction, then tensile strength improves, but bending fatigue resistance remains insufficient
Solution Approach 1:
The invention changes the critical parameters of particle size (100 nm or less) and number density (1.0 particles/μm² or more) to optimize both tensile strength and bending fatigue resistance. The high number density of ultrafine particles provides numerous barriers to crack propagation and stress concentration sites, significantly improving bending fatigue resistance beyond what conventional precipitation strengthening achieves.
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 solution achieves a copper alloy wire rod with high tensile strength, flexibility, conductivity, and bending fatigue resistance, exceeding requirements with a tensile strength of at least 320 MPa, elongation of 5%, and conductivity of 80% IACS, while maintaining a high number of bending cycles to fracture.
Implementation Method 1
silver added to copper emerges as a crystallized/precipitated product and has an effect of improving strength
Implementation Method 2
wire rods work-hardened by wire drawing or the like to improve the tensile strength
Implementation Method 3
wire rods heat-treated to improve the flexibility
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
It is an object of the present invention to provide a copper alloy wire rod having a high tensile strength, a high flexibility, a high conductivity and a high bending fatigue resistance at the same time. The copper alloy wire rod of the present invention is characterized by having a chemical composition comprising Ag: 0.1 to 6.0 mass% and P: 0 to 20 mass ppm, the balance being copper with inevitable impurities, in a cross section parallel to a longitudinal direction of the wire rod, a number density of second phase particles having an aspect ratio of greater than or equal to 1.5 and a size in a direction perpendicular to the longitudinal direction of the wire rod of less than or equal to 200 nm being greater than or equal to 1.4 particles/µm2.