Xiaochun Li

Dr. Xiaochun Li

Raytheon Chair in Manufacturing, Department of Mechanical and Aerospace Engineering and Department of Materials Science and Engineering, University of California, Los Angeles, CA, USA
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Research Focus & Metrics

Academic Career Length

33Years (1994-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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9 January 2019 in Nature Communications
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Journal Article
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MSMaximilian Sokoluk
Maximilian Sokoluk
CCChezheng Cao
Chezheng Cao
Shuaihang PanShuaihang Pan
Shuaihang Pan
Xiaochun LiXiaochun Li
Xiaochun Li
Lightweight materials are of paramount importance to reduce energy consumption and emissions in today’s society. For materials to qualify for widespread use in lightweight structural assembly, they must be weldable or joinable, which has been a long-standing issue for high strength aluminum alloys, such as 7075 (AA7075) due to their hot crack susceptibility during fusion welding. Here, we show that AA7075 can be safely arc welded without hot cracks by introducing nanoparticle-enabled phase control during welding. Joints welded with an AA7075 filler rod containing TiC nanoparticles not only exhibit fine globular grains and a modified secondary phase, both which intrinsically eliminate the materials hot crack susceptibility, but moreover show exceptional tensile strength in both as-welded and post-weld heat-treated conditions. This rather simple twist to the filler material of a fusion weld could be generally applied to a wide range of hot crack susceptible materials.

11 September 2019 in Nature Communications
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Journal Article
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TLTing-Chiang Lin
Ting-Chiang Lin
CCChezheng Cao
Chezheng Cao
MSMaximilian Sokoluk
Maximilian Sokoluk
LJLin Jiang
Lin Jiang
XWXin Wang
Xin Wang
Xiaochun LiXiaochun Li
Xiaochun Li
While laser-printed metals do not tend to match the mechanical properties and thermal stability of conventionally-processed metals, incorporating and dispersing nanoparticles in them should enhance their performance. However, this remains difficult to do during laser additive manufacturing. Here, we show that aluminum reinforced by nanoparticles can be deposited layer-by-layer via laser melting of nanocomposite powders, which enhance the laser absorption by almost one order of magnitude compared to pure aluminum powders. The laser printed nanocomposite delivers a yield strength of up to 1000 MPa, plasticity over 10%, and Young’s modulus of approximately 200 GPa, offering one of the highest specific Young’s modulus and specific yield strengths among structural metals, as well as an improved specific strength and thermal stability up to 400 °C compared to other aluminum-based materials. The improved performance is attributed to a high density of well-dispersed nanoparticles, strong interfacial bonding between nanoparticles and Al matrix, and ultrafine grain sizes.

1 May 2004 in Journal of Materials Science
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Xiaochun LiXiaochun Li
Xiaochun Li
YYYong Yang
Yong Yang
XCXudong Cheng
Xudong Cheng

9 May 2014 in Nature Communications
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Journal Article
Open access
LCLianyi Chen
Lianyi Chen
JXJia-Quan Xu
Jia-Quan Xu
HCHongseok Choi
Hongseok Choi
HKHiromi Konishi
Hiromi Konishi
SJSong Jin
Song Jin
Xiaochun LiXiaochun Li
Xiaochun Li
Effective control of phase growth under harsh conditions (such as high temperature, highly conductive liquids or high growth rate), where surfactants are unstable or ineffective, is still a long-standing challenge. Here we show a general approach for rapid control of diffusional growth through nanoparticle self-assembly on the fast-growing phase during cooling. After phase nucleation, the nanoparticles spontaneously assemble, within a few milliseconds, as a thin coating on the growing phase to block/limit diffusion, resulting in a uniformly dispersed phase orders of magnitude smaller than samples without nanoparticles. The effectiveness of this approach is demonstrated in both inorganic (immiscible alloy and eutectic alloy) and organic materials. Our approach overcomes the microstructure refinement limit set by the fast phase growth during cooling and breaks the inherent limitations of surfactants for growth control. Considering the growing availability of numerous types and sizes of nanoparticles, the nanoparticle-enabled growth control will find broad applications.

14 October 2009 in Metallurgical and Materials Transactions A
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MCMichael De Cicco
Michael De Cicco
HKHiromi Konishi
Hiromi Konishi
GCGuoping Cao
Guoping Cao
HCHong Seok Choi
Hong Seok Choi
LTLih-Sheng Turng
Lih-Sheng Turng
Xiaochun LiXiaochun Li
Xiaochun Li

13 May 2021 in Metallurgical and Materials Transactions A
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Journal Article
Closed access
PDF file
MSMaximilian Sokoluk
Maximilian Sokoluk
JYJie Yuan
Jie Yuan
SPShuaihang Pan
Shuaihang Pan
Xiaochun LiXiaochun Li
Xiaochun Li