On December 1st, "Science" magazine published a significant achievement by scientists at Chongqing University: Professor Huang Xiaoxu, Director of the Center for Electron Microscopy and a professor in the School of Materials Science and Engineering, and his team, using self-developed three-dimensional transmission electron microscopy technology, for the first time in the world, conducted research on the plastic deformation of nanometal and discovered an anomalous phenomenon where the internal crystal orientation of nanometal can be reversed after plastic deformation.
This significant breakthrough marks the Yellow Xiaoxu team's independently developed three-dimensional transmission electron microscopy technology, which, after more than a decade of development, has officially transitioned from principle to a mature application stage, achieving a leap from two-dimensional to three-dimensional research in nanomaterials.
Nanometallic materials, with their high strength and excellent wear resistance, have widespread applications and significant impacts. However, the causal relationship between the changes in the microstructure of the material and the alterations in its macroscopic properties remains to be revealed through scientific research. Traditional transmission electron microscopy techniques can only observe the two-dimensional projections of the three-dimensional internal structure of the material. Scientists have been seeking a new technology that can accurately characterize the three-dimensional structure of nanomaterials.
The Huang Xiaoxu team has long been committed to the research of advanced characterization techniques and nanometal materials. Over a decade ago, they proposed a novel method for direct three-dimensional quantitative characterization of nanocrystalline materials using transmission electron microscopy—the Transmission Electron Microscopy Three-Dimensional Orientation Reconstruction Technique. The principles of this pioneering technology were published in the journal "Science" in 2011.
"This technology has gone from theory to application over a decade," said Huang Xiaoxu. What appears to be a simple 3D image is actually a synthesis and extraction of crystal orientation information from hundreds of thousands of transmission electron microscope photos.
To ensure the technology's efficiency, accuracy, and practicality, the Huang Xiaoxu team has developed original R&D, creating an electron microscope electronic optics and image acquisition control system on the hardware side, which enhances the high-quality data collection speed of electron microscopes. On the software side, they developed an efficient data processing and analysis system as well as a 3D reconstruction system, transforming the internal structure of nanomaterials from 2D images into 3D maps. Leveraging these original technologies, they successfully developed a series of electron diffraction-based 3D transmission electron microscopy techniques, with the spatial resolution of the 3D orientation reconstruction technique reaching 1 nanometer (1 nanometer is equivalent to one millionth of a millimeter). These technologies fill the gap in nanoscale 3D orientation reconstruction techniques and will significantly accelerate the development of 3D materials science.
"Scanning Transmission Electron Microscopy (STEM) technology is a well-suited sword we have crafted for the study of nanomaterials," said Huang Tianlin, Professor of Materials Science and Engineering at Chongqing University and Deputy Director of the Electron Microscopy Center. With this powerful tool, we can accurately describe the individual crystals that make up nanomaterials. This not only lays the foundation for new theoretical models that establish relationships between microstructure and properties, but also provides guidance for developing new approaches to control and optimize the structure and properties of nanomaterials. Additionally, compared to the X-ray 3D characterization technology already in use in the field of materials science, the 3D orientation reconstruction technology of the transmission electron microscope raises the spatial resolution from the micrometer scale to the nanometer scale.
The Huang Xiaoxu team has also utilized the transmission electron microscopy three-dimensional orientation reconstruction technique to achieve the first study on the plastic deformation of nanometal, discovering an anomalous phenomenon of recoverable plastic strain in nanometal. This new finding enriches the theory of nanometal plastic deformation and will provide guidance for the development of advanced nanoscale structural materials, the prediction and control of nanomaterials' service behavior, and the optimization of micro-nano device functions.
"We are currently preparing to commercialize the technology of three-dimensional transmission electron microscopy," said Huang Xiaoxu. They plan to organically integrate the developed hardware and software technologies, allowing the integrated technology to be directly installed on traditional transmission electron microscopes, endowing them with three-dimensional characterization capabilities. This will facilitate material research in fields such as automotive manufacturing, aerospace, and microelectronic devices.
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