Laser additive manufacturing can be exploited to generate unique internally twinned nanoprecipitates in commercial titanium alloys, paving the way to fabricate ultrastrong metallic materials with intricate shapes for broad applications.
Ultrastrong nanotwinned titanium alloys through additive manufacturingTitanium alloys, widely used in the aerospace, automotive and energy sectors, require complex casting and thermomechanical processing to achieve the high strengths required for load-bearing applications. Here we reveal that additive manufacturing can exploit thermal cycling and rapid solidification to create ultrastrong and thermally stable titanium alloys, which may be directly implemented in service. As demonstrated in a commercial titanium alloy, after simple post-heat treatment, adequate elongation and tensile strengths over 1,600 MPa are achieved. The excellent properties are attributed to the unusual formation of dense, stable and internally twinned nanoprecipitates, which are rarely observed in traditionally processed titanium alloys. These nanotwinned precipitates are shown to originate from a high density of dislocations with a dominant screw character and formed from the additive manufacturing process. The work here paves the way to fabricate structural materials with unique microstructures and excellent properties for broad applications.
Nanotwinned α-precipitates in the LPBF microstructure after post-heat treatment (480 °C/6 h).
Yuman Zhu, Kun Zhang, Zhichao Meng, Kai Zhang, Peter Hodgson, Nick Birbilis, Matthew Weyland, Hamish L. Fraser, Samuel Chao Voon Lim, Huizhi Peng, Rui Yang, Hao Wang & Aijun Huang
doi: 10.1038/s41563-022-01359-2 | |
The authors use circularly polarized light pulses to trigger all-optical magnetization switching in an atomically thin ferromagnetic semiconductor. The switching process is related to spin angular momentum transfer from photoexcited carriers to local magnetic moments.
All-optical switching of magnetization in atomically thin CrI3Control of magnetism has attracted interest in achieving low-power and high-speed applications such as magnetic data storage and spintronic devices. Two-dimensional magnets allow for control of magnetic properties using the electric field, electrostatic doping and strain. In two-dimensional atomically thin magnets, a non-volatile all-optical method would offer the distinct advantage of switching magnetic states without application of an external field. Here, we demonstrate such all-optical magnetization switching in the atomically thin ferromagnetic semiconductor, CrI3, triggered by circularly polarized light pulses. The magnetization switching behaviour strongly depends on the exciting photon energy and polarization, in correspondence with excitonic transitions in CrI3, indicating that the switching process is related to spin angular momentum transfer from photoexcited carriers to local magnetic moments. Such an all-optical magnetization switching should allow for further exploration of magneto-optical interactions and open up applications in high-speed and low-power spintronic devices.
All-optical magnetization switching in atomically thin magnetic crystal of CrI3 and sample characterization.
Peiyao Zhang, Ting-Fung Chung, Quanwei Li, Siqi Wang, Qingjun Wang, Warren L. B. Huey, Sui Yang, Joshua E. Goldberger, Jie Yao & Xiang Zhang
doi: 10.1038/s41563-022-01354-7 | |
Angle tunability in twisted bilayer graphene is crucial in promoting its applications of twistronics. Here an angle replication strategy is developed to obtain centimetre-scale bilayer graphene with arbitrary twist angles.
Designed growth of large bilayer graphene with arbitrary twist anglesThe production of large-area twisted bilayer graphene (TBG) with controllable angles is a prerequisite for proceeding with its massive applications. However, most of the prevailing strategies to fabricate twisted bilayers face great challenges, where the transfer methods are easily stuck by interfacial contamination, and direct growth methods lack the flexibility in twist-angle design. Here we develop an effective strategy to grow centimetre-scale TBG with arbitrary twist angles (accuracy, <1.0°). The success in accurate angle control is realized by an angle replication from two prerotated single-crystal Cu(111) foils to form a Cu/TBG/Cu sandwich structure, from which the TBG can be isolated by a custom-developed equipotential surface etching process. The accuracy and consistency of the twist angles are unambiguously illustrated by comprehensive characterization techniques, namely, optical spectroscopy, electron microscopy, photoemission spectroscopy and photocurrent spectroscopy. Our work opens an accessible avenue for the designed growth of large-scale two-dimensional twisted bilayers and thus lays the material foundation for the future applications of twistronics at the integration level.
Schematic for the growth design of TBG.
Can Liu, Zehui Li, Ruixi Qiao, Qinghe Wang, Zhibin Zhang, Fang Liu, Ziqi Zhou, Nianze Shang, Hongwei Fang, Meixiao Wang, Zhongkai Liu, Zuo Feng, Yang Cheng, Heng Wu, Dewei Gong, Song Liu, Zhensheng Zhang, Dingxin Zou, Ying Fu, Jun He, Hao Hong, Muhong Wu, Peng Gao, Ping-Heng Tan, Xinqiang Wang, Dapeng Yu, Enge Wang, Zhu-Jun Wang & Kaihui Liu
doi: 10.1038/s41563-022-01361-8 | |
Solid-state electrolytes are key to the development of safer and higher-energy-density batteries. Using liquid electrolyte chemistries as models for polymer electrolytes, the effect of adding a variety of porous and dense ceramic electrolytes on the conductivity is now investigated.
Dense inorganic electrolyte particles as a lever to promote composite electrolyte conductivitySolid-state batteries are seen as key to the development of safer and higher-energy-density batteries, by limiting flammability and enabling the use of the lithium metal anode, respectively. Composite polymer–ceramic electrolytes are a possible solution for their realization, by benefiting from the combined mechanical properties of the polymer electrolyte and the thermal stability and high conductivity of the ceramic electrolyte. In this study we used different liquid electrolyte chemistries as models for the polymer electrolytes, and evaluated the effect of adding a variety of porous and dense ceramic electrolytes on the conductivity. All the results could be modelled with the effective medium theory, allowing prediction of the conductivity of electrolyte combinations. We unambiguously determined that highly conductive porous particles act as insulators in such systems, whereas dense particles act as conductors, thereby advancing our understanding of composite electrolyte conductivity.
Possible factors that can affect the effective conductivity of composite electrolytes.
James A. Isaac, Didier Devaux & Renaud Bouchet
doi: 10.1038/s41563-022-01343-w | |
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