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Processing of Bulk Nanocrystalline Metals at the US Army Research Laboratory
Published on: March 7, 2018
Nanostructured bulk copper fabricated by accumulative roll bonding.
Naoki Takata1, Seong-Hee Lee, Cha-Yong Lim
1Department of Adaptive Machine Systems, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Journal of Nanoscience and Nanotechnology
|December 1, 2007
Summary
Severe plastic deformation via accumulative roll-bonding (ARB) created nanostructured copper alloys with enhanced strength. This process refined microstructures, significantly boosting tensile strength while maintaining ductility.
Area of Science:
- Materials Science
- Metallurgy
- Nanotechnology
Background:
- Conventional copper alloys often face limitations in strength-ductility balance.
- Severe plastic deformation (SPD) offers a route to engineer advanced material properties.
Purpose of the Study:
- To fabricate nanostructured bulk copper alloys using SPD.
- To investigate the microstructural evolution and mechanical properties of copper alloys processed by accumulative roll-bonding (ARB).
Main Methods:
- Copper alloy sheets (OFC, PMC90, DLP) were subjected to severe plastic deformation using the ARB process to an equivalent strain of 6.4.
- Microstructural analysis and mechanical property testing (tensile strength, elongation) were performed on the fabricated specimens.
Main Results:
- The ARB process refined the microstructure, creating ultrafine lamellar structures with mean lamella spacing around 200 nm.
- Tensile strength significantly increased with decreasing lamella spacing, reaching 520 MPa for DLP alloys (8 cycles, strain 6.4), a threefold improvement.
- Total elongation initially dropped but recovered to 10% after 8 ARB cycles, attributed to increased post-uniform elongation.
Conclusions:
- Nanostructured copper alloy sheets with high strength and retained ductility can be successfully fabricated using the ARB process.
- The ARB process is effective in overcoming the typical strength-ductility trade-off in copper alloys.
- The study demonstrates a viable method for producing advanced copper alloys for demanding applications.
