Cu-Si-Co Alloy Spring Limit via Multi-Stage Aging
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Solution Overview
Problem
Cu-Si-Co-based copper alloys for electronic components face limitations in achieving superior spring limit, strength, and conductivity, despite advancements in precipitation-hardened copper alloys.
Innovation Solution
A Cu-Si-Co-based alloy with specific composition (0.5-2.5% Co, 0.1-0.7% Si, and controlled Ni, Cr, and other impurities, subjected to a multi-stage aging treatment under precise temperature and time conditions, enhancing the distribution of second-phase particles and crystal orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional solid solution-strengthened copper alloys (phosphor bronze, brass) are used, then manufacturing is simpler, but strength and electrical conductivity are insufficient
Solution Approach 1:
The invention changes the material parameters by transitioning from solid solution strengthening to precipitation hardening mechanism. This involves controlling the composition parameters (Co: 0.5-2.5 mass%, Si: 0.1-0.7 mass%) and heat treatment parameters (solution treatment at 850-1050°C followed by aging at 300-500°C) to achieve fine precipitate formation, thereby simultaneously improving strength and electrical conductivity
Solution Approach 2:
The invention creates a composite microstructure consisting of a copper matrix with dispersed fine precipitates of Co-Si-based intermetallic compounds. This composite structure at the micro-scale provides both high strength through precipitate reinforcement and high electrical conductivity through the continuous copper matrix, resolving the contradiction between strength and conductivity
2Strength
If Cu-Si-Co-based alloy with standard aging treatment is used, then production process is simpler, but spring limit is insufficient
Solution Approach 1:
The invention segments the aging process into multiple stages with different temperature and time parameters. The first aging stage (300-400°C for 1-24 hours) forms initial precipitates, while the second aging stage (400-500°C for 1-24 hours) coarsens and redistributes them. This segmented approach creates an optimized precipitate distribution that significantly improves spring limit compared to single-stage aging
Solution Approach 2:
The invention employs periodic heat treatment cycles consisting of solution treatment followed by two sequential aging treatments. This periodic thermal processing creates rhythmic precipitation and coarsening cycles that optimize the precipitate morphology and distribution, thereby enhancing spring limit while maintaining a systematic production process
3Strength
If multi-stage aging treatment is applied to improve spring limit, then mechanical properties improve, but production time and process complexity increase
Solution Approach 1:
The invention merges the solution treatment and hot rolling operations into a combined high-temperature processing step performed at 850-1050°C. This merging eliminates separate heating and cooling cycles, reducing production time while maintaining the necessary microstructure for subsequent multi-stage aging treatment to achieve high spring limit
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 exhibits improved strength, conductivity, and spring limit, with a peak height ratio of diffraction peaks at least 2.5 times that of standard copper, achieving a balanced performance in mechanical and electrical properties.
Implementation Method 1
a supersaturated solid solution, which has been subjected to solution treatment, is subjected to ageing treatment, whereby fine precipitates are homogeneously dispersed and not only the strength but also the electrical conductivity of the alloy are increased
Implementation Method 2
step 5 of performing solution treatment at 950-1050°C, and then cooling the material temperature with an average cooling rate of at least 15°C/sec from 850°C to 400°C
Implementation Method 3
step 4 of aging treatment at 350-500°C for 1-24 hours; step 7 of ageing treatment
Implementation Method 4
step 2 of heating the ingot to 950-1050°C for at least one hour and thereafter subjecting it to hot rolling, setting the temperature at the time of completion of the hot rolling to at least 850°C
Data Source
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AI summary
A Cu-Si-Co-based alloy having an enhanced spring limit is provided. The copper alloy comprises 0.5-2.5 mass% of Co, 0.1-0.7 mass% of Si, the balance Cu and inevitable impurities, wherein, from a result obtained from measurement of an X ray diffraction pole figure, using a rolled surface as a reference plane, a peak height at 6 angle of 90° among diffraction peaks in {111} Cu plane with respect to {200} Cu plane by 6 scanning at α=35° is at least 2.5 times that of a standard copper powder.