Pomelo Peel Inspires High-Impact Alloy

An impact-resistant aluminum-silicon structural material inspired by an unusual source—the peel of the pomelo fruit—comes from Sebastian F. Fischer of Germany’s RWTH Aachen University and colleagues (J. Mater. Sci. 2013, DOI: 10.1007/s10853-013-7878-4). Lightweight materials that can take a beating are sought after for many applications, particularly in the automotive industry. Materials scientists often use structures found in nature, such as needlelike structures of deep-sea sponges and cellulose fibrils in wood, as their inspiration for a particular material design. Pomelos are not as well explored, but their thick pithy peel protects the large, heavy citrus fruit when falling 30 feet or more from the tree to the ground. The peel is built of a foam with struts consisting of cell wall material and liquid. Fischer and his coworkers used a block mold casting process to transfer the pomelo strut structure to the new material, which is made up of aluminum-silicon alloy shells filled with pure aluminum. The structured material has a higher ductility than the aluminum-silicon alloy alone.