Influence of δ' Phase with GP‑I Zones Fillings on Slip Behavior and Cold Rolling Texture in AA2099

Xusheng Yang,Weijiu Huang,Xianghui Zhu,Fei Guo,Yanlong Ma,Linjiang Chai,Ran Zhang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9

The cold rolling texture of AA2099 sheets was strongly influenced by the prior heat treatment. Two typical heat treatments,including solid solution (T4) and underaging (T6) were utilized to control slip behavior by different precipitates during coldrolling. A much weaker texture with an orientation scatter towards higher Φ angles was found in the as-rolled T6 specimen(T6R). Slip behavior was analyzed using geometry necessary boundaries distribution. Results show that the T6R specimenexperienced a strong co-planar slip compared to the as-rolled T4 specimen. Prosperity of co-planar slips and limitation ofco-direction slips were main reasons for the weakening of Copper texture component in the T6R specimen. The distinguishslip behavior was caused by existence of δ' phase with GP-I zones fillings in the T6 specimen. This phase could be easilysheared by dislocations and then promoted co-planar slips in further deformation.

Characterization of the Hot Deformation Behaviour of an As-Extruded Al–Cu–Li Alloy by Constitutive Analysis

Xusheng Yang,Weijiu Huang,Xianghui Zhu,Ran Zhang,Fei Guo,Li Hu 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

The true stress–strain curves of an as-extruded state AA2099 were determined by uniaxial compression tests under varioushot deformation regimes. Constitutive analysis of the curves allowed calculation of the hot deformation activation energy(QHW). The microstructure of the as-compressed specimens were also characterized by electron back scatter diffraction(EBSD). EBSD data analyses showed that the major restoration mechanism corresponding to common industrial extrusionregimes was dynamic recovery. The precipitates in three states (T83, as-homogenized, and as-extruded) were characterizedby X-ray diffraction (XRD) phase analyses and transmission electron microscopy. The results revealed that the QHWwasclosely relevant to the precipitates strengthening. The finite element method simulation results and the microstructure of theextruded products confirmed that AA2099 in as-extruded state possessed good workability.

Exact solutions of axisymmetric free vibration of transversely isotropic magnetoelectroelastic laminated circular plates

Chen, Jiangying,Xu, Rongqiao,Huang, Xusheng,Ding, Haojiang Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.23 No.2

The axisymmetric free vibrations of transversely isotropic magnetoelectroelastic laminated circular plates are studied. Based on the three-dimensional governing equations of magnetoelectroelastic medium, the state space equations of laminated circular plates are obtained. By using the finite Hankel transform and rendering the free terms left by the transform in terms of the boundary quantities, the solutions of the state space equations are given for two kinds of boundary conditions. The frequency equations of the free vibration are derived using the propagator matrix method and the boundary conditions at top and bottom surfaces. By virtue of the inverse Hankel transform, the mode shapes are also determined. Since the solutions strictly satisfy the governing equations in the region and the boundary conditions at the edges, they are the three-dimensionally exact. Finally, the natural frequencies of such plates are tabulated and compared with those of the piezoelectric and elastic plates in the numerical example.

Secondary Short-Lasting Unilateral Neuralgiform Headache with Conjunctival Injection and Tearing: A New Case and a Literature Review

Ya Cao,Fei Yang,Zhao Dong,Xusheng Huang,Bingzhen Cao,Shengyuan Yu 대한신경과학회 2018 Journal of Clinical Neurology Vol.14 No.4

Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) is a primary headache syndrome with an unclear pathogenesis. However, there is increasing evidence in the literature for secondary SUNCT being attributable to certain known lesions. We explored the possible neurobiological mechanism underlying SUNCT based on all reported cases of secondary SUNCT for which detailed information is available. Here we report a case of neuromyelitis optica spectrum disorders that had typical symptoms of SUNCT that might have been attributable to involvement of the spinal nucleus of the trigeminal nerve. We also review cases of secondary SUNCT reported in the English-language literature and analyze them for demographic characteristics, clinical features, response to treatment, and imaging findings. The literature review shows that secondary SUNCT can derive from a neoplasm, vascular disease, trauma, infection, inflammation, or congenital malformation. The pons with involvement of the trigeminal root entry zone was the most commonly affected region for inducing secondary SUNCT. In conclusion, the neurobiology of secondary SUNCT includes structures such as the nucleus and the trigeminal nerve with its branches, suggesting that some cases of primary SUNCT have underlying mechanisms that are related to existing focal damage that cannot be visualized.

Microstructure Evolution and Mechanical Properties of AA2099 Al–Li Alloy with Tailored Li‐Containing Precipitates in Uniaxial Compression at Medium Temperature

Li Hu,Mengdi Li,Weijiu Huang,Xusheng Yang,Fei Guo,Haipeng Dong 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5

Microstructure characteristics and mechanical behavior of AA2099 Al–Li alloy with no pre-existing Li-containing precipitates(AA2099-1 sample), pre-existing δ′ precipitates (AA2099-2 sample), pre-existing T1phase (AA2099-3 sample) andpre-existing T2phase (AA2099-4 sample) are systematically investigated via isothermal uniaxial compression at 250 °C inthe present study. Experimental results demonstrate that at the onset of plastic deformation, dynamic precipitation of smallsizedT1phase occurs rapidly within AA2099-1 sample, while it will be hindered within AA2099-2 sample. The increasingplastic strain benefits to dynamic precipitation of small-sized T1phase in AA2099-2 sample. Consequently, AA2099-1 andAA2099-2 samples possess similar and intermediate mechanical behaviors. In terms of AA2099-3 sample, the existence oflarge-sized T1phase results in the maximum yielding stress. However, some regions within these large-sized T1precipitatesare suspected to be sheared by cross-slip, leading to the destruction of crystallographic structure and the formation of Almatrix intervals. This aspect is responsible for the gradual degradation in true stress-strain curve after peak stress. As forAA2099-4 sample, dynamic precipitation rarely happens during plastic deformation and the interaction between dislocationand the pre-existing T2phase belongs to Orowan looping, resulting in the minimal mechanical response. Besides,AA2099-1 sample possesses the average minimum deviation angle (MDA) of ~ 16.5° between the loading direction and the<110> crystal direction, whereas AA2099-4 sample owns the average MDA of ~ 7.5°. The difference in MDA is mainlyattributed to δ′ phase and T1phase, which will separately accelerate and postpone the rotation of orientation towards the<110> crystal direction.

Assembly of micro/nanomaterials into complex, three-dimensional architectures by compressive buckling

Xu, Sheng,Yan, Zheng,Jang, Kyung-In,Huang, Wen,Fu, Haoran,Kim, Jeonghyun,Wei, Zijun,Flavin, Matthew,McCracken, Joselle,Wang, Renhan,Badea, Adina,Liu, Yuhao,Xiao, Dongqing,Zhou, Guoyan,Lee, Jungwoo,Chu American Association for the Advancement of Scienc 2015 Science Vol.347 No.6218

<P><B>Popping materials and devices from 2D into 3D</B></P><P>Curved, thin, flexible complex three-dimensional (3D) structures can be very hard to manufacture at small length scales. Xu <I>et al.</I> develop an ingenious design strategy for the microfabrication of complex geometric 3D mesostructures that derive from the out-of-plane buckling of an originally planar structural layout (see the Perspective by Ye and Tsukruk). Finite element analysis of the mechanics makes it possible to design the two 2D patterns, which is then attached to a previously strained substrate at a number of points. Relaxing of the substrate causes the patterned material to bend and buckle, leading to its 3D shape.</P><P><I>Science</I>, this issue p. 154; see also p. 130</P><P>Complex three-dimensional (3D) structures in biology (e.g., cytoskeletal webs, neural circuits, and vasculature networks) form naturally to provide essential functions in even the most basic forms of life. Compelling opportunities exist for analogous 3D architectures in human-made devices, but design options are constrained by existing capabilities in materials growth and assembly. We report routes to previously inaccessible classes of 3D constructs in advanced materials, including device-grade silicon. The schemes involve geometric transformation of 2D micro/nanostructures into extended 3D layouts by compressive buckling. Demonstrations include experimental and theoretical studies of more than 40 representative geometries, from single and multiple helices, toroids, and conical spirals to structures that resemble spherical baskets, cuboid cages, starbursts, flowers, scaffolds, fences, and frameworks, each with single- and/or multiple-level configurations.</P>