Invited Speaker
Dr. Yanli Lu
Professor, State Key Laboratory of Solidification ProcessingNorthwestern Polytechnical University, China
Speech Title: Microstructure Characterization of Nano-Al Particles and its Effect on Mechanical Properties of Aluminum Alloy
Abstract: Various orientations and diffraction patterns from nanoscale Al precipitates in eutectic Si were investigated by high-resolution transmission electron microscopy combined with transition matrix and stereographic projection. It was found that the Al precipitates had 12 variants, all orientation relationships can be expressed as: (001)Al//{111}Si, [110]Al//<110 >Si. Further, a new diffraction pattern model from Al precipitates was established under [111]Si zone axis, which was in good agreement with the experiment data. The microstructure, adhesion strength and electronic structure of the interface between Al precipitate and Si matrix were studied by first-principles calculation and experimental observation. The results show that the covalent bonds are formed between interfacial Al and Si atoms, which play a key role in interfacial bind strength. Based on the Griffith fracture theory, the cracks tend to form and expand in the interior of Al precipitates firstly, and the interfaces can act as a protective layer to prevent crack propagation. Therefore, the nanoscale Al precipitates will improve the toughness of eutectic Si particles by releasing part of stress through lattice distortion. In addition, the stretched nanoscale Al precipitates can act as effective heterogeneous nucleation sites for high density deformation nanotwins in eutectic Si during deformation, which significantly improved the deformability of eutectic Si.
Biography: Lu Yanli is the professor and doctoral supervisor from School of Materials Science and Engineering, Northwestern Polytechnical University. She is mainly engaged in multi-scale research on the microstructure and properties of advanced metal materials and functional materials. She presided over 15 projects including four National Natural Science Foundation projects and Shaanxi Provincial Natural Science Foundation projects, published more than 100 SCI papers, and authorized 4 national invention patents. She served as the reviewer for SCI journals such as Computational Materials Science and "Science China Series". She has won Shaanxi Science and Technology Award, Chinese Society of Aeronautics and Astronautics Science and Technology Award, Aviation Society of Youth Science and Technology Award in Shaanxi Province, etc.