Guest Speaker: Prof. ZHANG Zhuhua
Institute of Nano Science
Nanjing University of Aeronautics and Astronautics
Zhang Zhuhua, Professor at Nanjing University of Aeronautics and Astronautics and Director of the Talent Affairs Office; received the National Science Fund for Distinguished Young Scholars, selected for the National High-Level Talents Program, and appointed as a Jiangsu Specially-Appointed Professor. He has been engaged in research on nanoscale physical mechanics, with over 180 papers published in journals such as Science, Nature Mater., Nature Nanotech., and PRL. His work has been cited more than 10,000 times in SCI-indexed publications, and he has been the Highly Cited Chinese Scholars from (2020-2024). His awards include the Second Prize of the National Natural Science Award (third contributor), the Youth Science and Technology Award from the Chinese Society of Theoretical and Applied Mechanics (CSTAM), the Young Teachers Award from the Huo Yingdong Education Foundation, and the First Prize in Natural Science from the Ministry of Education. He serves as Vice Director of the Physical Mechanics Committee of the CSTAM, member of the Solid Mechanics Committee of CSTAM, Associate Editor of the International Journal of Smart and Nano Materials, and the Acta Mechanica Solida Sinica.
Abstract
Two-dimensional materials (2DMs) are prone to brittle failure under load but a recent experiment has demonstrated intrinsic toughening in hexagonal boron nitride (BN), which calls for a general understanding of fracture toughness in 2DMs. In this report, we used atomistic calculations combined with a developed linear-scaling method to show that 2DMs with strong anisotropy of edge energy favor bifurcated cracks for intrinsic toughening as in h-BN, while those with weak edge energy anisotropy exhibit split cracks for brittle failure as in graphene. We also develop a robust descriptor for identifying 2DMs exhibiting similar fracture behavior to that in h-BN and reach a physically interpretable formula capable of quantitatively determining the toughness of 2DMs based on easily accessible intrinsic features of elements. Then, we also revealed interesting dependence of the fracture behaver of bilayer BN on the stacking registry and twist angle. We find that the fracture roughness of the most favourable AA’ stacking is reduced to half the value of single layer BN, while a small interlayer twist can raise the fracture roughness to be remarkably higher than the single layer value. We show that the toughening mechanism by twist can vary from loose coupling, interference to cross-layer bonding with increasing the twist angle.
