Cu-Zr-Sn Alloy Sheet for Balanced Conductivity and Strength
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Solution Overview
Problem
Existing copper alloys struggle to achieve a balance between high conductivity, strength, and stress relaxation resistance, with limitations on the use of third elements like Sn, leading to increased costs and restricted production processes.
Innovation Solution
A Cu-Zr-Sn based copper alloy is developed with combined additions of Zr and Sn, introducing sufficient strain through hot and cold rolling processes, followed by aging treatment to precipitate fine second phase particles and enhance crystal lattice strain, resulting in a sheet material with high conductivity and strength while maintaining stress relaxation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Sn is added to improve strength and stress relaxation resistance, then tensile strength and stress relaxation ratio are improved, but conductivity deteriorates
Solution Approach 1:
The patent applies parameter changes by strictly controlling the Sn content within 0.01-0.50 mass% and Zr content within 0.03-0.50 mass%, along with controlling the ratio between them. This precise parameter control allows the alloy to achieve tensile strength of 450 MPa or more and stress relaxation ratio of 25% or less at 200°C for 1000 hours, while maintaining conductivity of 75.0% IACS or more. The controlled composition enables simultaneous improvement of strength and stress relaxation resistance without significant conductivity deterioration.
Solution Approach 2:
The patent creates a composite material system by combining Cu-Zr-Sn alloy with specific heat treatment processes (solution treatment at 850-980°C followed by aging at 250-650°C). This composite approach produces a microstructure containing fine second phase particles (Cu3Zr and Cu6Sn5) dispersed in the Cu matrix, achieving tensile strength of 450 MPa or more and stress relaxation ratio of 25% or less at 200°C for 1000 hours, while maintaining conductivity of 75.0% IACS or more.
2Reliability
If Cr and third elements are added to improve conductivity and strength, then conductivity and tensile strength are improved, but stress relaxation resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the composition parameters (Zr: 0.03-0.50 mass%, Sn: 0.01-0.50 mass%) and heat treatment parameters (solution treatment temperature: 850-980°C, aging temperature: 250-650°C). This precise control achieves a balance where conductivity is 75.0% IACS or more, tensile strength is 450 MPa or more, and stress relaxation ratio is 25% or less at 200°C for 1000 hours, resolving the contradiction between conductivity and stress relaxation resistance.
Solution Approach 2:
The patent creates a composite material system by combining Cu-Zr-Sn alloy with specific heat treatment processes. The solution treatment dissolves Zr and Sn into the Cu matrix, and the subsequent aging treatment precipitates fine second phase particles (Cu3Zr and Cu6Sn5). This composite approach achieves conductivity of 75.0% IACS or more, tensile strength of 450 MPa or more, and stress relaxation ratio of 25% or less at 200°C for 1000 hours.
3Ease of manufacture
If general copper scraps are used to reduce cost, then manufacturing cost is reduced, but production process complexity increases
Solution Approach 1:
The patent applies parameter changes by defining specific composition ranges (Zr: 0.03-0.50 mass%, Sn: 0.01-0.50 mass%) that allow the use of general copper scraps containing Sn impurities. The controlled composition ensures that even with scrap material variability, the final product achieves conductivity of 75.0% IACS or more, tensile strength of 450 MPa or more, and stress relaxation ratio of 25% or less at 200°C for 1000 hours, simplifying the production process by eliminating the need for extremely strict scrap selection.
Solution Approach 2:
The patent applies local quality by allowing Sn content up to 0.50 mass% (which would be considered an impurity in traditional high-conductivity copper alloys) in specific ranges. This localized tolerance for Sn content enables the use of general copper scraps with Sn impurities while still achieving the target properties (conductivity of 75.0% IACS or more, tensile strength of 450 MPa or more, stress relaxation ratio of 25% or less at 200°C for 1000 hours) through the combined Cu-Zr-Sn system and heat treatment, thereby reducing manufacturing cost without significantly increasing production process complexity.
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 Cu-Zr-Sn alloy achieves a conductivity of 75.0% IACS or more and a tensile strength of 450 MPa or more, allowing for the use of general copper scraps and a simpler production process, while maintaining excellent stress relaxation resistance characteristics, thus offering a cost-effective solution comparable to or exceeding traditional Cu-Zr alloys.
Implementation Method 1
introducing sufficient strain through hot and cold rolling processes
Implementation Method 2
followed by aging treatment to precipitate fine second phase particles
Implementation Method 3
aging treatment to precipitate fine second phase particles and enhance crystal lattice strain
Data Source
AI summary
To provide a copper alloy sheet material having a copper alloy component system capable of being produced with general scraps of copper based material that has a high conductivity of 75.0% IACS or more and has both a high strength and good stress relaxation resistance characteristics in a well balanced manner. A copper alloy sheet material having a chemical composition containing, in terms of percentage by mass, from 0.01 to 0.50% of Zr, from 0.01 to 0.50% of Sn, a total content of from 0 to 0.50% of Mg, Al, Si, P, Ti, Cr, Mn, Co, Ni, Zn, Fe, Ag, Ca, and B, with the balance of Cu, and unavoidable impurities, and having a metal structure having a number density NA of fine second phase particles having a particle diameter of approximately from 5 to 50 nm of 10.0 per 0.12 µm2 or more and a ratio NB/NA of a number density NB (per 0.012 mm2) of coarse second phase particles having a particle diameter exceeding approximately 0.2 µm and the NA of 0.50 or less.