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Topic: Nanomaterials Multi-scale Elastic-plastic Mechanics andMechanical System Integration

Speaker: Prof. Lu Jian

Vice-President (Research and Technology) of City University of Hong Kong;

Academician ofNational Academy of Technologies of France

Time: 15:00, May 13, 2019 (Monday)

Venue: Auditorium 401, College of Mechanical and Vehicle Engineering

Welcome to join us!

Brief introduction of Prof. Lu Jian:

Prof. Lu Jian is an academician of the National Academy of Technologies of France, and the vice-president (Research and Technology) and chair professor of Mechanical Engineering of City University of Hong Kong. He is also dean of Chow Yei Ching School of Graduate Studies, and former president of Hong Kong Society of Theoretical and Applied Mechanics. His research focuses on the mechanical performance and preparation of advanced structure andfunctional nanomaterials, andmechanical system analogue simulation design.

Prof. Lu Jian has published more than papers on peer-reviewedjournals, including Nature (featured as cover), Science, Nature Materials, Materials Today, Advanced Materials, Advanced Functional Materials,Nature Communications, Science Advances, PRL, Acta Materialia, Journal of the Mechanics and Physics of Solids (JMPS) and the citation is more than 16,000 times. He served as an evaluation expert for 5thFramework Programme for Research and Technological Development;a member of the Expert Panel for 6thFramework Programme for Research and Technological Development; and an overseas assessor of the Chinese Academy of Sciences and National Nature Science Foundation of China.

Structural nanomaterials and metallic amorphous materials are the fastest growing high strength materials with broad prospects. However, low deformation capacity and lack of commercial alloy restrict their applications in industry and structural domain. This talk would systematically introduce the progress made by our group in the fracture mechanism of hierarchical nano-twin materials ([1]-[4]) and metallic glass, and the fabrication method of toughing materials ([5]-[8]). We have studied several experimental methods of multi-scale mechanics to character the fracture property and mechanism of metallic glass. Experiments such as high-frequency dynamic micropillar tests and fast beta relaxation tests are developed to character structural defects at the atomic scale of metallic glass. The results can be used to study structure evolution process at the atomic scale of the failure process. Recently, our group have successfully fabricated supra-nanometre-sized (<10nm) dual-phase glass-crystal high-strength magnesium alloys and nanoscale diamond with ultralarge elastic deformation ([9]-[10]). Since the scale of the crystalline phase is around six nanometres in diametre, almost no dislocation occurs during the loading process, and the material strength reaches the near-ideal strength (E/20). The new supra-nanometre-sized structure has brought new material family that different from grain boundary for material scientist. The new structure would change the physical and chemical properties relevant to ultrasmall grain and grain boundary, and provide a new direction for the development of ultralarge elastic nanomaterials. In the end, I will introduce the application prospects of the supra-namometre-sized material and hierarchical nanomaterials in microsystems and biomedical engineering, and some cases of structure design of material integration. Applications of multi-stable morphable nanostructured materials in aerospace and underwater lifting system, 4d printed dual-phase nanoceramis ([11]), and challenges and opportunities.


References:

[1]H.N.Kou, J.Lu, Y.Li,High-Strength and High-Ductility Nanostructured and Amorphous Metallic Materials,Advanced Materials, 2014,26, Pages 5518–5524

[2] L.L.Zhu, S.Q.Qu, X.Guo, J.Lu, Analysis of the twin spacing and grain size effects on mechanical properties in hierarchically nanotwinned face-centered cubic metals based on a mechanism-based plasticity model,Journal of the Mechanics and Physics of Solids, Volume:76, Pages:162-179, March 2015

[3] X.W.Liu, L.G.Sun, L.L.Zhu, J.B.Liu, K.Lu, J.Lu, High-order hierarchical nanotwins with superior strength and ductility,Acta Materialia, 1stMay 2018, pages 397-406

[4] A.Y.Chen, L.L.Zhu, L.G.Sun, J.B.Liu, H.T.Wang, X.Y.Wang, J.H.Yang, J.Lu, Scale law of complex deformation transitions of nanotwins in stainless steel,Nature Communications, 29 March, 2019, https://doi.org/10.1038/s41467-019-09360-1

[5] J.C.Ye,J.Lu,C.T.Liu, Q.Wang, Y.Yang, Atomistic Free-Volume Zones and Inelastic Deformation of Metallic-Glasses Characterized by High-Frequency Dynamic Micropillar Tests,Nature Materials, Volume 9, Issue 8, August 2010,Pages 619-623.

[6]Q.Wang, S.T.Zhang, Y.Yang, Y.D.Dong, C.T.Liu, J.Lu, Unusual fast secondary relaxation in metallic glass,Nature Communications, 24 Jul 2015, DOI: 10.1038/ncomms8876

[7]Q.Wang,J.J.Liu, Y.F.Ye, T.T.Liu, S.Wang, C.T.Liu, J.Lu, Y.Yang, Universal secondary relaxation and unusual brittle-to-ductile transition in metallic glasses.Materials Today,Volume 20, Issue 6, July–August 2017, Pages 293-300

[8] Q.Wang, C.T.Liu, Y.Yang, Y.D.Dong, J.Lu,Atomic-Scale Structural Evolution and Stability of Supercooled Liquid of a Zr-Based Bulk Metallic Glass,Physical Review Letters,May 2011, Volume 106, Issue 21, N.215505

[9]G.Wu, K.C.Chan, L.L.Zhu, L.G.Sun, J.Lu,Dual-phase nanostructuring as a route to high strength magnesium alloys,Nature,4thMay 2017, Pages:80-83

[10]A.Banerjee, D.Bernoulli, H.T.Zhang, M.F.Yuen, J.B.Liu, J.C.Dong, F.Ding, J.Lu, M.Dao, WJ.Zhang,Y.Lu, S.Suresh, Ultralarge elastic deformation of nanoscale diamond,Science, 20 April2018, Vol. 360, Issue 6386, pp. 300-302

[11] G.Liu, Y.Zhao, G.Wu, J.Lu,Origami and 4D printing of elastomer-derived ceramic structures,Science Advances, 17 August 2018;4:eaat0641, pp1-10

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