Nanotwinned Metals

Nicholas A. Richter, Mingyu Gong, Yifan Zhang, Tongjun Niu, Bo Yang et al. "Exploring the deformation behavior of nanotwinned Al-Zr alloy via in-situ compression" Journal of Applied Physics 132 (2022): 065104.

https://doi.org/10.1063/5.0098497

Highlight: This study highlights the impressive strengths achieved by Al-Zr alloys containing abundant incoherent twin boundaries and 9R phase. The strongest alloy reaches a hardness of 4.2 GPa and a flow stress of 1.0 GPa, while maintaining significant deformability.

Qiang Li, Jaehun Cho, Sichuang Xue, Xing Sun, Yifan Zhang, Zhongxia Shang, Haiyan Wang, and Xinghang Zhang. "High temperature thermal and mechanical stability of high-strength nanotwinned Al alloys." Acta Materialia 165 (2019): 142-152.

https://doi.org/10.1016/j.actamat.2018.11.011 

Highlight: This study demonstrates superb the thermal stability in magnetron sputtered Al-Fe alloy films, with the Fe solute stabilizing the 9R phase and incoherent twin boundaries up to ~280 °C. At annealing temperatures above 300 °C, a nanocomposite forms, leading to the drastic softening

Sichuang Xue, Zhe Fan, Olawale B. Lawal, Ramathasan Thevamaran, Qiang Li, Yue Liu, K. Y. Yu et al. "High-velocity projectile impact induced 9R phase in ultrafine-grained aluminium." Nature communications 8(1) (2017): 1-9. 

https://doi.org/10.1038/s41467-017-01729-4 

Highlight: Despite the high stacking fault energy in Al, this study demonstrates that high strain rate impact can introduce both incoherent twin boundaries and 9R phase. The shock induces the migration of partial dislocations, which leads to the formation of 9R phase.

Bufford, D., Y. Liu, Y. Zhu, Z. Bi, Q. X. Jia, H. Wang, and X. Zhang. "Formation mechanisms of high-density growth twins in aluminum with high stacking-fault energy." Materials Research Letters 1, no. 1 (2013): 51-60. 

https://doi.org/10.1080/21663831.2012.761654

Highlight: Using Ag/Al multilayers, a template method is identified in this study for replicating incoherent and coherent twin boundaries from the low stacking fault energy (SFE) Ag into the high SFE Al layer. Coherent metal interfaces are identified to be crucial for twin formation in high SFE metal layers.

Left image: O. Anderoglu, A. Misra, H. Wang, F. Ronning, M. F. Hundley, and X. Zhang. "Epitaxial nanotwinned Cu films with high strength and high conductivity." Applied Physics Letters 93, no. 8 (2008): 083108.

https://doi-org.ezproxy.lib.purdue.edu/10.1063/1.2969409 

Right image: D. Bufford., H. Wang, and X. Zhang. "High strength, epitaxial nanotwinned Ag films." Acta Materialia 59, no. 1 (2011): 93-101. 

https://doi.org/10.1016/j.actamat.2010.09.011

Highlight: Magnetron sputtering thermodynamically traps nanotwins in metals with low SFE metals easily (left image - Cu; right image - Ag). This leads to a high degree of strenghtening as well as high conductivity (Cu) and thermal stability, without sacrificing ductility

Tongjun Niu, Ke Xu, Chao Shen, Tianyi Sun, Justin Oberst, Carol A. Handwerker, Ganesh Subbarayan, Haiyan Wang, and Xinghang Zhang. "In Situ Study on Cu-to-Cu Thermal Compression Bonding." Crystals 13, no. 7 (2023): 989. 

https://doi.org/10.3390/cryst13070989 

Highlight:  The in situ TCB method enables a real-time observation of bonding development, which provides critical insights into how the texture and microstructure of Cu bumps may influence the creep and surface diffusion during the bonding process. 

Nicholas A. Richter, Xuanyu Sheng, Bo Yang, Benjamin Thomas Stegman, Haiyan Wang, and Xinghang Zhang. "Assessing Strain Rate Sensitivity of Nanotwinned Al–Zr Alloys through Nanoindentation." Crystals 13, no. 2 (2023): 276. 

https://doi.org/10.3390/cryst13020276 

Highlight:  A modified nanoindentation method has been employed here to accurately determine the strain rate sensitivity of nanotwinned Al–Zr alloys. The hardness of these alloys reaches 4.2 GPa while simultaneously exhibiting an improved strain rate sensitivity. The nanotwinned Al–Zr alloys have shown grain size-dependent strain rate sensitivity, consistent with previous findings in the literature. This work provides insight into a previously unstudied aspect of nanotwinned Al alloys.