Cu-Mg-P Alloy Strength-Conductivity Balance
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Solution Overview
Problem
Cu-Mg-based alloys face issues with insufficient conductivity, cold workability, and bendability due to high Mg content, and Cu-Mg-P alloys form coarse precipitates leading to reduced strength and anisotropy, making them unsuitable for applications requiring high conductivity and strength.
Innovation Solution
A copper alloy with Mg content between 0.15 and 0.35 mass% and P content between 0.0005 and 0.01 mass%, optimized to improve strength, stress relaxation resistance, and castability, while maintaining high electrical conductivity and reducing anisotropy by controlling crystal orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high Mg content (0.01-0.5 mass%) is used in Cu-Mg alloy, then strength is improved, but conductivity deteriorates and coarse precipitates form reducing cold workability and bendability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Mg content within 0.01-0.5 mass% and P content within 0.01-0.5 mass%, optimizing the balance between strength and conductivity. This quantitative parameter optimization resolves the contradiction by finding the optimal range where strength is sufficiently improved while conductivity and cold workability are maintained
Solution Approach 2:
The patent creates a composite alloy system by combining Cu-Mg-P with optional additional elements (Si, Mn, Fe, Ni, Zn, Sn, Pb, Ti, Al, B, rare earth elements). This composite approach allows the base Cu-Mg-P alloy to provide strength enhancement while the controlled composition maintains conductivity and cold workability, resolving the technical contradiction through material composition design
2Strength
If Mg content is increased to improve strength, then stress relaxation resistance is improved, but electrical conductivity decreases
Solution Approach 1:
The patent resolves this contradiction through parameter changes by limiting Mg content to 0.01-0.5 mass%, which is sufficient to improve stress relaxation resistance through solid solution strengthening and precipitate formation, while remaining low enough to maintain electrical conductivity above 75% IACS. The simultaneous addition of P (0.01-0.5 mass%) further optimizes the stress relaxation properties without significantly impacting conductivity
3Strength
If high strength is achieved through alloying, then strength is improved, but anisotropy increases reducing bendability
Solution Approach 1:
The patent addresses this contradiction through parameter changes by optimizing the Mg content (0.01-0.5 mass%) and P content (0.01-0.5 mass%) to achieve a balanced microstructure. This controlled composition produces fine and uniform precipitates rather than coarse ones, reducing anisotropy and maintaining good bendability even while achieving high strength. The synergistic effect of Mg and P at these specific concentrations resolves the strength-bendability contradiction
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 achieves excellent electrical conductivity, strength, and bendability with reduced anisotropy, making it suitable for high-current applications and minimizing cracking during bending, while also enhancing castability.
Implementation Method 1
the strength and the stress relaxation resistance can be improved without greatly decreasing the electrical conductivity by solid melting Mg in the Cu matrix phase since the Mg content is in the range of 0.15 mass% or more and less than 0.35 mass%
Implementation Method 2
By adding P, the viscosity of the molten copper alloy containing Mg can be lowered, and castability can be improved.
Implementation Method 3
since a strength ratio TS TD /TS LD , which is calculated from strength TS TD obtained in a tensile test performed in a direction perpendicular to a rolling direction and strength TS LD obtained in a tensile test performed in a direction parallel to a rolling direction, is more than 0.9 and less than 1.1
Implementation Method 4
a ratio of crystals having a crystal orientation within 10° with respect to a Brass orientation {110} is 40% or less, and a ratio of crystals having a crystal orientation within 10° with respect to a Copper orientation {112} is 40% or less
Data Source
Figure 1
AI summary
A copper alloy for an electronic and electric device is provided. The copper alloy includes: Mg in a range of 0.15 mass% or more and less than 0.35 mass%; and a Cu balance including inevitable impurities, wherein the electrical conductivity of the copper alloy is more than 75%IACS, and a strength ratio TSTD/TSLD, which is calculated from strength TSTD obtained in a tensile test performed in a direction perpendicular to a rolling direction and strength TSLD obtained in a tensile test performed in a direction parallel to a rolling direction, is more than 0.9 and less than 1.1. The copper alloy may further include P in a range of 0.0005 mass% or more and less than 0.01 mass%.