Improving cyclic deformation responses of nanostructured metallic materials via tuning the stacking fault energy and microstructures
材料学院青促会学术交流报告
报告人:悉尼大学 安祥海
博士
报告题目:Improving cyclic deformation
responses of nanostructured
metallic materials via tuning the
stacking fault energy and microstructures
地点:浙江大学玉泉校区曹光彪楼326会议室
时间:2017年05月26日(星期五)
14:30
邀请人:秦发祥
材料学院青年教师发展促进会承办
Abstract: With respect to the perspective
engineering applications of nanostructured (NS) metallic materials, apart from
the strength and ductility under monotonic loading, their cyclic deformation
response is another essentially crucial concern owning to safety issues.
Compared with their CG references, NS materials generally exhibit enhanced
high-cycle fatigue (HCF) and decreased low-cycle fatigue (LCF) properties in
the light of the dependence of fatigue lives on the stress and strain
amplitudes, respectively. Our recent investigations revealed that prominent
improvement of the LCF lives and HCF strengths, especially fatigue endurance
limits, of NS metals and alloys, can be simultaneously achieved with decreasing
their stacking fault energy (SFE). These upgraded fatigue performances with
lowering the SFE in NS materials can be attributed not only to the simultaneous
increase of their monotonic strength and ductility in macroscale, but also to
the crucially decreased cyclic softening behavior in terms of grain coarsening
and shear banding in microscale. In addition, the dominant fatigue damage
micro-mechanism was also transformed inherently from extensive grain boundary
(GB) migration to other local GB activities such as atom shuffling
or GB
sliding/rotation with the reduction of the SFE. Owing to the limitation of
their intrinsic fatigue mechanisms, the
fatigue endurance limits of NS metals and alloys cannot always acquire
appreciable improvement with their monotonic strengths. However, tuning the
microstructures to harvest recrystallized nanostructures can significantly
enhance the fatigue strength of NS materials despite the lower tensile
strength. These results enable us to timely exploit the knowledge of fatigue
behavior of NS metallic materials, which is important both scientifically, for
the in-depth comprehension of their deformation behavior, and technologically,
for assessing their service utilities in safety-critical structural components,
and also open up promising venues for materials design to possess optimal
mechanical properties.
Brief
Bio: Xianghai An
received his PhD degree in Materials Fatigue and Fracture Division, Shenyang
National Laboratory for Materials Sciences, Institute of Metal Research,
Chinese Academy of Sciences.
After receiving PhD degree, he joined the School of Aerospace,
Mechatronic and Mechanical Engineering at The University of Sydney as a
research fellow, then DVCR research fellow supported by University and is
currently a DECRA fellow supported by Australia ARC. He was also conferred on
the Alexander von Humboldt Fellowship by Humboldt Foundation in Germany.
Dr. Xianghai An’s
research mainly focuses on understanding the microstructures, deformation
mechanisms, and mechanical behavior of advanced metallic materials by recourse
to extensive microscopy characterization and mechanical testing. Up to date,
more than 40 papers with citation and h-index of 990 and 18 (Google Scholar),
respectively, have been published in top journals including Nano letters, Acta Materialia, Scripta Materialia, and
Applied Physics Letters.
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