Nano-Twin Copper Material for High Strength and Conductivity
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Solution Overview
Problem
Current methods to strengthen copper and its alloys result in a significant decrease in electrical conductivity, making it challenging to achieve high strength and conductivity simultaneously, especially in applications requiring high precision, reliability, and microminiaturization.
Innovation Solution
The development of nano-twin copper material with ultrahigh strength and high electrical conductivity is achieved through a pulsed electrodeposition technique, producing submicron-sized grains with twin lamellar structures, maintaining a high density of coherent twin boundaries and low dislocation density, which enhances tensile yield strength while preserving conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If grain refinement is used to strengthen copper, then strength increases, but electrical conductivity decreases
Solution Approach 1:
The copper material is segmented into nanoscale grains (1-100 nm) with high density of coherent twin boundaries, creating a fine-grained microstructure that strengthens the material while maintaining conductivity through the specific nanocrystalline architecture
Solution Approach 2:
The invention creates a composite microstructure within pure copper combining nanocrystalline grains and coherent twin boundaries, achieving ultrahigh strength (900 MPa) and high conductivity (96% IACS) simultaneously without adding alloying elements
2Strength
If alloying is used to increase strength, then strength increases by two or three times, but electrical conductivity decreases dramatically
Solution Approach 1:
The invention extracts the strengthening mechanism from alloying elements and achieves it through microstructural control (nanocrystalline grains and twin boundaries) in pure copper, eliminating the harmful effect on electrical conductivity while maintaining ultrahigh strength
Solution Approach 2:
The invention changes the microstructural parameters (grain size to nanoscale, twin boundary density) rather than changing chemical composition, achieving strength enhancement without the conductivity penalty associated with alloying
3Strength
If minim Fe and Ni are added to increase strength, then strength increases, but magnetic property is affected
Solution Approach 1:
The invention removes the need for Fe and Ni alloying elements by using microstructural strengthening mechanisms, thereby eliminating the harmful magnetic properties while achieving ultrahigh strength in pure copper
4Strength
If nanocrystalline structure is created to increase strength, then strength increases, but when grain size is too small, softening effect appears
Solution Approach 1:
The invention optimizes the grain size parameter to the nanoscale range (1-100 nm) and controls twin boundary density to achieve the optimal balance where grain boundaries provide strengthening without causing softening, maintaining both strength and mechanical stability
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 nano-twin copper material exhibits a tensile yield strength of 900 MPa and electrical conductivity of 96% IACS, offering improved mechanical properties and thermal stability suitable for advanced industries like computer and radio communication.
Implementation Method 1
The Cu materials with high density nano-scale twin lamellae structures were prepared by means of pulsed electrodeposition technique
Implementation Method 2
Electrolysis processing parameters: pulsed current density of 50 A/cm2 with a on-time (ton) of 0.02 s and off-time (toff) of 2 s
Data Source
AI summary
The present invention relates to a nanocrystalline metallic material, particularly to nano-twin copper material with ultrahigh strength and high electrical conductivity and its preparation method. High-purity polycrystalline Cu material with a microstructure of roughly equiaxed submicron-sized grains (300-1000 nm) has been produced by pulsed electrodeposition technique, by which high density of growth-in twins with nano-scale twin spacing were induced in the grains. Inside each grain, there are high densities of growth-in twin lamellae. The twin lamellae with the same orientations are inter-parallel, and the twin spacing ranges from several nanometers to 100 nm with a length of 100-500 nm. This Cu material invented has more excellent performance than existing ones. The tensile yield strength and ultimate strength of the present Cu material at room-temperature can be as high as 900 MPa and 1086 MPa, respectively, and such a high tensile strength can not be achieved for the Cu materials with the same chemical composition prepared by any traditional methods. Meanwhile, the present Cu sample also keeps a good electrical conductivity, for example, the room-temperature resistivity is (1.75±0.02)×10−8 Ω·m, corresponding to 96% IACS, which is close to that of the conventional coarse-grained Cu.