Cu-Co-Si Alloy Microstructure Control for Strength and Conductivity
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Solution Overview
Problem
Cu—Co—Si-based copper alloys face challenges in achieving high strength, electrical conductivity, and anti-setting properties, particularly in applications as spring materials, where permanent deformation is a concern, and the precise measurement of fine precipitates is difficult due to their small size.
Innovation Solution
The alloy composition is optimized with 0.5 to 3.0% Co, 0.1 to 1.0% Si, and controlled distribution of second-phase particles with specific size ranges (5 nm to 50 nm) and ratios to enhance strength, electrical conductivity, and anti-setting properties, along with a manufacturing process involving solution treatment, ageing, and cold rolling to achieve a well-balanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Cu—Ni—Si-based alloy is used to achieve high strength through precipitation hardening, then strength is improved, but electrical conductivity cannot reach 60% IACS or higher
Solution Approach 1:
The patent changes the alloying element parameter from Ni to Co, creating a Cu—Co—Si-based alloy system. This parameter change results in lower solute content of cobalt silicide compared to nickel silicide, thereby improving electrical conductivity to 60% IACS or higher while maintaining high strength through precipitation hardening of Co—Si intermetallic compounds
Solution Approach 2:
The patent creates a composite microstructure consisting of a copper matrix with dispersed Co—Si intermetallic compound precipitates. This composite structure allows the matrix to provide high electrical conductivity while the precipitates provide strength through precipitation hardening, resolving the contradiction between strength and conductivity
2Strength
If ageing is performed to precipitate fine particles for improving strength and conductivity, then mechanical properties and electrical conductivity are improved, but precise control of particle distribution and size is difficult
Solution Approach 1:
The patent optimizes ageing parameters (temperature and time) to control the precipitation behavior of Co—Si intermetallic compounds. By adjusting these parameters, the patent achieves uniform dispersion of fine precipitates with controlled size and distribution, improving both mechanical properties and electrical conductivity while overcoming the difficulty of precise particle control
Solution Approach 2:
The patent establishes a relationship between ageing conditions and precipitate characteristics, using this knowledge as feedback to optimize the ageing process. By understanding how ageing temperature and time affect particle size and distribution, the patent can precisely control the microstructure to achieve the desired balance of strength and conductivity
3Reliability
If Cu—Co—Si-based alloy is used to achieve higher electrical conductivity than Cu—Ni—Si-based alloy, then electrical conductivity is improved, but it is difficult to achieve both high conductivity and high strength simultaneously
Solution Approach 1:
The patent changes the composition parameters to optimize the balance between conductivity and strength. By controlling the Co and Si content within specific ranges and optimizing the ageing treatment, the patent achieves both high electrical conductivity (60% IACS or higher) and high strength through controlled precipitation hardening of Co—Si intermetallic compounds
Solution Approach 2:
The patent creates a composite microstructure with a copper matrix providing high electrical conductivity and Co—Si intermetallic compound precipitates providing strength. This composite structure resolves the contradiction by separating the functions of conductivity and strength enhancement into different phases
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 optimized Cu—Co—Si-based copper alloy achieves excellent strength, electrical conductivity, and anti-setting properties, with improved bendability, effectively addressing the limitations of existing alloys by precisely controlling the distribution and size of second-phase particles.
Implementation Method 1
In the precipitation hardening copper alloys, age hardening of supersaturated solid solution after solution treatment facilitates uniform dispersion of fine precipitates
Implementation Method 2
age hardening of supersaturated solid solution after solution treatment facilitates uniform dispersion of fine precipitates
Implementation Method 3
allowing fine particles of Ni—Si-based intermetallic compound to precipitate in a copper matrix
Implementation Method 4
Processes largely influential to characteristics of the Cu—Co—Si-based copper alloy are exemplified by solution treatment, ageing, and final rolling
Data Source
AI summary
Disclosed is a Cu—Co—Si-based copper alloy for electronic materials, which is capable of achieving high levels of strength, electrical conductivity, and also anti-setting property; and contains 0.5 to 3.0% by mass of Co, 0.1 to 1.0% by mass of Si, and the balance of Cu and inevitable impurities; wherein out of second phase particles precipitated in the matrix a number density of the particles having particle size of 5 nm or larger and 50 nm or smaller is 1×1012 to 1×1014 particles/mm3, and a ratio of the number density of particles having particle size of 5 nm or larger and smaller than 10 nm relative to the number density of particles having particle size of 10 nm or larger and 50 nm or smaller is 3 to 6.