My main research thrust revolves around thermoplastic forming, additive manufacturing /3D imprinting, draw forming and electromagnetic forming of metallic materials, such as bulk metallic glasses (BMGs), aluminum alloys and composites etc., in which plentiful of fundamental issues including formability, processing, microstructure, mechanical properties and possible applications are concerned. Specifically, taking advantages of BMGs’ superplastic features in the supercooled liquid region, we developed a wide range of thermoplastic processing methods, fabricated various micro-scale parts/patterns and cellular structures, investigated forming mechanisms and exploited potential applications in superhydrophobic functionalization and MEMS device integration. BMGs have advanced a new era of structural materials since late 1960s due to their unique combination of mechanical, physical, and chemical properties benefiting from the disordered atomic arrangement. The Achilles’s heel challenge in commercialization of BMGs is however severely limited in forming and manufacturing. Selective Laser Melting (SLM) based 3D printing technique developed in recent years offers a novel route to processing of BMGs. We launched the research of 3D printing of BMGs since 2014. In this realm, a wide range of activities have been taken in understanding the mechanistic principles in laser printing as well as the associated fundamental issues and phenomena such as spatial thermal/residual stress, processing induced defects, microstructural evolution and mechanical properties of the as-printed parts at multiple length scales. On a different note, we have being very active in exploring electromagnetic forming to process Aluminum alloys in an efficient and highly practical fashion. Herein, the specific influence of processing conditions such as strain rate on the mechanical response and microstructural variation has been scrutinized.
(1) N. Li*, X.N. Xu, Z.Z. Zheng, L. Liu*, Enhanced formability of a Zr-based bulk metallic glass in supercooled liquid state by vibrational loading, Acta Materialia, 65, 2014, 400-411.
(2) N. Li, Y. Chen, M.Q. Jiang, D.J. Li, J.J. He, Y. Wu, L. Liu*, Thermoplastic forming map of a Zr-based bulk metallic glass, Acta Materialia, 61, 2013, 1921-1931.
(3) N. Li*, T. Xia, L.P. Heng, L. Liu*, Superhydrophobic Zr-based metallic glass surface with high adhesive force, Applied Physics Letters 102, 2013, 251603.
(4) N. Li*, D.J. Li, L. Liu, Correlation between flow characteristics and interfacial friction behavior of a Zr-based metallic glass during micro-extrusion, Philosophical Magazine, 93, 2013, 1859-1872.
(5) T. Xia, N. Li*, Y. Wu, L. Liu*, Patterned superhydrophobic surface based on Pd-based metallic glass, Applied Physics Letters 101, 2012, 081601.