报告题目：Play with defects: new insights into the size-dependent plasticity
报告内容简介：The size-dependent plasticity of small-scale metals that are the critical components to the architecture of micro/nano-electro-mechanical systems (M/NEMS) has been attracting dramatic attention over the last two decades. The well-known size effect manifested as “smaller is stronger” indicates that at micron and submicron scales, the sample dimensions of materials play essential roles in controlling the mechanical properties and deformation physics. Classic crytal plasticity enligthens us that tuning stacking fault energy (SFE) via alloying provides a robust protocol to manipulate deformation mechanism and consequently the mechanical properties of metallic materials. However, the effects of SFE on the size-dependent plasticity have rarely been studied. Herein, we firstly employed quantitative in-situ deformation transmission electron microscopy to systematically uncover the size effects on the mechanical properties and deformation mechanisms of Cu–Al single-crystalline nanopillars because the SFE was controlled by adjusting the Al content in Cu–Al alloys. Size-dependent mechanical behaviour and deformation mechanism were comprehensively explored, which were controlled by the interplay among sample size, SFE and alloying induced short-range ordering. Moreover, compared to the conventional metals with single SFE, the novel high-entropy alloy with high compositional complexity exhibits a wide spectrum of “local” SFE due to the statistical fluctuation in the compositional and packing arrangements of the various elements. We found that the joint and/or sequential activations of the displacive deformation mechanisms originated from chemical compositional heterogeneities at the atomic level enables the room-temperature super-elongation in high-entropy alloy nanopillars, which was rarely observed in small-volume metals with high strenght and low ductility.
报告人姓名：Xianghai An
报告人简介：Dr Xianghai An is a Senior Lecturer and Associated Head in School of Aerospace, Mechanical and Mechatronic Engineering at The University of Sydney and serve as an Associate Head (research training). He obtained his PhD in Shenyang National Laboratory for Materials Sciences, Institute of Metal Research, Chinese Academy of Sciences in 2012. After receiving PhD degree, he commenced with the School of AMME as a research fellow, qualifying as a DVCR Research Fellow, an ARC DECRA and Robinson Fellowship. He was also conferred to the Alexander von Humboldt Fellowship by Humboldt Foundation in 2016 and Dean’s Research Award for 2018. He is the one recipient, in Faculty of Engineering, of the inaugural Robinson Fellowships named after Sir Robert Robinson who was the first Nobel Prize winner in USYD. Dr. An’s research spans from atomic-scale plasticity to the nanomechanics of individual microstructural features, and the mechanical performance of bulk engineering materials. His dedicated efforts aim to build a fundamental understanding of deformation mechanisms, material architectures, and the intricate interplay between structures and properties across different length scales, and develop new approaches for engineering hierarchical heterogeneous nanostructures, pushing the boundaries of materials properties. He has so far published over 90 papers in top peer-reviewed journals in the fields of materials and mechanical engineering. Recent papers are in prestigious journals such as Science, Science Advances, Nature communications, Progress in Materials Science, Applied Physics Review, Acta Materialia, International Journal of Plasticity, Additive Manufacturing. The significant impact of my research is evidenced by the high citations of ~5800 (Google Scholar) and H-index of 44. He also obtained First Prize of Fundamental Research in Materials Sci .& Tec., Chinese Materials Research Society (Rank 2/15).
报告人单位：悉尼大学
报告时间：2024-07-12 09:00
报告地点：材料楼520
