Cu-Ag Alloy Wire Composition for Ultrafine Strength and Conductivity
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Solution Overview
Problem
Existing Cu—Ag-based alloy wires face challenges in achieving high tensile strength, electrical conductivity, and bending fatigue resistance, particularly when reduced in diameter, due to embrittlement during heat treatment and lack of appropriate wire drawing processes.
Innovation Solution
A Cu—Ag-based alloy wire with a specific composition and microstructural control, including a matrix phase and Ag phase precipitates, with controlled Ag concentrations and ratios in surface and central regions, along with controlled processing parameters like cooling rates and wire drawing ratios, to enhance tensile strength and fatigue resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the wire diameter is reduced to achieve miniaturization, then the electrical conductivity and strength-to-weight ratio improve, but the tensile strength and bending fatigue resistance deteriorate due to embrittlement
Solution Approach 1:
The patent applies local quality by creating a non-uniform Ag concentration distribution within the wire cross-section. The surface region contains 1.5-4.0 mass% Ag while the central region contains 0.5-2.0 mass% Ag. This gradient structure provides surface hardening for strength while maintaining core ductility, resolving the contradiction between miniaturization and strength retention.
Solution Approach 2:
The patent changes the chemical composition parameters by controlling Ag concentration at different radial positions. By adjusting the Ag content gradient (c1-c2 value) and absolute concentrations in surface and central regions, the material achieves optimized mechanical properties for ultrafine wires, transforming the uniform composition approach into a controlled compositional gradient.
2Strength
If heat treatment is applied to develop recrystallization texture to improve strength, then the tensile strength increases, but embrittlement progresses making wire thinning difficult
Solution Approach 1:
The patent applies preliminary action by establishing the optimal Ag concentration gradient (c1-c2 = 1.00-3.00 mass%) before final wire drawing. This pre-positioned compositional structure enables subsequent heat treatment to develop recrystallization texture and achieve high strength (950-1450 MPa) without causing excessive embrittlement that would prevent further thinning.
Solution Approach 2:
The patent changes the material's compositional parameters to resolve the strength-ductility trade-off. By controlling Ag concentration in specific ranges (surface: 1.5-4.0 mass%, center: 0.5-2.0 mass%) and maintaining a specific concentration difference (c1-c2: 1.00-3.00 mass%), the material achieves both high tensile strength and sufficient ductility for continued processing.
3Strength
If Ag content is increased to improve tensile strength, then the strength increases, but electrical conductivity deteriorates
Solution Approach 1:
The patent applies local quality by spatially separating the functions of strength and conductivity through radial concentration gradients. The surface region (higher Ag: 1.5-4.0 mass%) provides strength through precipitation hardening, while the central region (lower Ag: 0.5-2.0 mass%) maintains electrical conductivity. This resolves the contradiction by allowing high overall Ag content (3.0-6.0 mass%) without uniform conductivity loss.
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 alloy wire achieves high tensile strength, high electrical conductivity, and improved bending fatigue resistance, enabling the production of ultrafine wires suitable for electronic device connections and speaker coils.
Implementation Method 1
having a metal structure including a Cu alloy phase as a matrix phase and a second phase precipitate containing an Ag phase
Data Source
AI summary
A Cu—Ag-based alloy wire, including an alloy composition containing 1.00-6.00 mass % of Ag, with a balance being Cu and inevitable impurities, having metal structure including a matrix phase of Cu alloy phase and a second phase precipitate containing an Ag phase, having ≥950 MPa tensile strength when containing 1.00 mass %≤Ag<1.50 mass %, ≥1050 MPa tensile strength when containing 1.50 mass %≤Ag<3.00 mass %, ≥1200 MPa tensile strength when containing 3.00 mass %≤Ag<5.00 mass %, and ≥1450 MPa tensile strength when containing 5.00 mass %≤Ag≤6.00 mass %, and when L is a linear distance from a surface to a center in a transection of the wire, c1 is an Ag average concentration in a annular region having L/100 length from the surface towards the center, and c2 is an Ag average concentration in a central region having 99L/100 length from the center toward the surface, (c1-c2) being 1.00-3.00 mass %.