Mechanical Behaviors of Nanotwinned Metals and Nanotwinned Covalent Materials

Metallic and covalent materials are important structural materials. Traditional strategies for strengthening materials compromise their ductility and toughness. Recent experimental results show that twinning can simultaneously improve the strength (hardness) and toughness of copper and diamond; as the inverse relationship between the strength and toughness of materials is broken, this has become a hot research topic. By studying the strengthening mechanism of nanotwinned copper and diamond, methods to simultaneously improve strength and toughness may be found. Herein, this paper presents a comprehensive overview of the recent developments in the experimental and theoretical studies of nanotwinned metals and covalent materials. The microstructures, fabrication methods, and mechanical properties of nanotwinned metals and covalent materials are summarized. Further, the strengthening mechanism of nanotwinned metals and the hardening mechanism of covalent materials are introduced. Finally, the research trend on the mechanical behavior of nanotwinned materials is discussed in detail.