A research team led by Professors Weitao Zheng and Kan Zhang from the College of Materials Science and Engineering at Jilin University, in collaboration with Professor Changfeng Chen from the University of Nevada, Las Vegas, has made a significant breakthrough in structural material design. Their study, entitled “Bamboo-like dual-phase nanostructured copper composite strengthened by amorphous boron framework”, was recently published in Nature Communications. The team reports a novel bamboo-like copper–boron nanocomposite thin film structure that achieves a rare combination of high hardness, strength, and ductility.

Bamboo-inspired Cu–B composite: balancing strength and ductility

Achieving high hardness and strength without sacrificing ductility remains a central challenge in the development of structural materials. Grain boundary engineering is an effective strategy to optimize mechanical performance by tailoring the composition and bonding structures at grain interfaces. In nanocrystalline materials, grain boundaries play a decisive role in determining mechanical behavior, especially under complex loading conditions.

Inspired by nature, particularly the hierarchical structure of bamboo—which combines hard sheath fibers with a compliant matrix to achieve excellent toughness—the team designed a bioinspired thin film microstructure. They introduced immiscible boron into a copper matrix using magnetron co-sputtering deposition. This bottom-up process produced a continuous bamboo-like nanocolumn structure, where an amorphous boron framework reinforces nanocrystalline copper segments.

The amorphous boron shell plays a critical role in stabilizing the soft copper phase by suppressing shear-induced instabilities during indentation, allowing compressive strength to dominate and thereby improving hardness. During micropillar compression testing, the bamboo-like architecture significantly mitigated shear-induced failure, leading to improved ductility and mechanical integrity.

The result is a nanostructured Cu–B thin film with an impressive hardness of 10.8 GPa, along with yield strength of ~1.36 GPa, flow stress of ~2.58 GPa, and failure strain exceeding 50%, showcasing outstanding mechanical synergy between strength and ductility.

New insights for strong and tough materials

This study introduces a new approach to structural material design: combining immiscible metal-light element systems with a bottom-up fabrication process to create bamboo-like architectures. This provides a promising pathway for achieving strength–toughness synergy in advanced structural materials, offering valuable insights into microstructural engineering for strong and ductile systems.

Hang Lv (master’s student) and Xinxin Gao (Ph.D. candidate) from Jilin University are co-first authors of the paper. Professor Kan Zhang and Dr. Chang Liu are corresponding authors. The study was supported by the National Natural Science Foundation of China, the China Postdoctoral Science Foundation, and the Natural Science Foundation of Jilin Province.

Related article:
Hang Lv#, Xinxin Gao#, Kan Zhang*, Mao Wen, Xingjia He, Zhongzhen Wu, Chang Liu*, Changfeng Chen, Weitao Zheng,
“Bamboo-like dual-phase nanostructured copper composite strengthened by amorphous boron framework”,
Nature Communications, 14, 4836 (2023).
https://doi.org/10.1038/s41467-023-40580-8