Design of Hierarchical Cellular Metals Using Accumulative Bundle Extrusion
- PDF / 563,390 Bytes
- 6 Pages / 593.972 x 792 pts Page_size
- 60 Downloads / 172 Views
Rapid progress of technology and complex systems requires new multifunctional materials. Cellular[1] and porous[2] materials are attractive because they provide a wide range of properties in solids and allow for specific applications requiring features such as low relative density, light weight, good energy and sound absorption, heat dissipation, and large surface area. The architecture and properties of cell walls are two primary factors that determine the overall performance of the cellular material. Research on conventional methods for manufacturing cellular materials has concentrated only on one of the above factors, often at the expense of the other. For example, techniques involving powders and liquid metals are used to create cellular materials and foams with a vast range of topologies, while the specific strength of such materials is limited because these methods include high-temperature procedures. In this regard, solid-state fabrication of cellular metals at low temperatures is attracting interest. An example of a solid-state fabrication approach can be found in an earlier study,[3] where obtaining porous copper with a high specific strength was reported. However, the importance of the architecture and MARAT I. LATYPOV and DONG JUN LEE, Ph.D. Candidates, and HYOUNG SEOP KIM, Professor, are with the Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea. Contact e-mail: [email protected] HA-GUK JEONG, Director, and JONG BEOM LEE, Senior Researcher, are with the Production Technology R&D Department, Korea Institute of Industrial Technology, Incheon 406-840, Republic of Korea. Manuscript submitted December 20, 2012. Article published online June 25, 2013 METALLURGICAL AND MATERIALS TRANSACTIONS A
hierarchy in cellular materials has not been addressed in the research particularly focused on high specific strength, whereas studies dedicated to the architecture and hierarchy[4–8] have demonstrated that a periodic arrangement of cell walls is superior to a nonperiodic arrangement, while hierarchical structures have advantages over their nonhierarchical counterparts. Overall, techniques that combine both the advantageous architecture and high cell-wall strength appear to be missing. The current study develops a simple and relatively inexpensive method for producing cellular metals with high specific strength and diverse architecture, including hierarchical ones. It is demonstrated that characteristics of the cellular metal such as hierarchy, periodicity, selfsimilarity, and properties of the cell-wall material can be manipulated at different scales. In the proposed method, the procedure of producing cellular metals comprises two principal steps: (i) accumulative extrusion of at least two metals to form a fiberreinforced composite containing an interconnected matrix; (ii) selective removal of the cores, which serve as ‘‘mandrels’’ for the matrix cells. Accumulative extrusion is the first step where a precursor composite of a core–shell ty
Data Loading...
