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| 1 | High-temperature mechanical properties of as-extruded AZ80 magnesium alloy at different strain rates显示文摘The mechanical properties of as-extruded AZ80 magnesium alloy at temperatures of 450-525℃ and strain rates of 3.0 s^(−1)and 0.15 s^(−1)were investigated by tensile tests.Zero ductility of alloy appeared at 500℃ with a strain rate of 0.15 s^(−1),while the zero strength and zero ductility of the alloy were obtained nearly simultaneously at 525℃ with a strain rate of 3.0 s^(−1).The results indicated that the lower strain rate accelerated the arrival of zero ductility.As the temperature increased,the failure mode of the alloy developed from trans-granular fracture to cleavage fracture and then to inter-granular fracture with the feature of sugar-like grains and fusion traces.The existence of the low-melting composite ofβ-Mg_(17)Al_(12) and Al_(8)Mn_(5) particles segregated near the Mg_(17)Al_(12) phase along grain boundaries were demonstrated to be the reason for the brittle fracturing of the AZ80 alloy at high temperatures.Furthermore,microstructural evolution at temperatures approaching the solidus temperature was discussed to clarify magnesium alloy’s high temperature deformation mechanism. | Wenjun Liu Bin Jiang Hongchen Xiang Qing Ye Shengqi Xia Siqiang Chen Jiangfeng Song Yanlong Ma Mingbo Yang | 2022 | International Journal of Minerals,Metallurgy and Materials2022，29，7： | 3 |
| 2 | Capturing the baroclinic effect in non-Boussinesq gravity currents显示文摘Direct numerical simulations of two-dimensional gravity currents with small and medium density variations are performed using different non-Boussinesq buoyancy approximations. Taking the full low-Machnumber approximation as the reference, the accuracy of several buoyancy terms are examined. It is found that all considered buoyancy terms performed well in the cases with small density variation. In the cases with medium density variation, the classical gravitational Boussinesq’s buoyancy term showed the lack of accuracy, and a simple correction did not make any improvement. In contrast, the recently introduced second-order buoyancy term showed a significantly higher accuracy. The present results and our previous derivations indicate that simple algebraic buoyancy approximations extended from the Boussinesq’s gravitational buoyancy are unlikely to achieve an accuracy beyond first order. Instead, it seems necessary to solve at least one extra Poisson equation for buoyancy terms to capture the higher-order baroclinic effect. An approximate analysis is also provided to show the leading term of the non-Boussinesq effect corresponding to gravity. | Shengqi Zhang Zhenhua Xia | 2022 | Theoretical & Applied Mechanics Letters2022，12，1： | 0 |
| 3 | MICROSTRUCTURE AND MECHANICAL PROPERTIES OF IN-SITU FORMATION FIBROUS POLYTYPE AlN COMPOSITE-MATERIAL显示文摘In-situ formation fibrous polytype AlN composite ceramic materials was prepared fromAlN-Y2O3-SiO2 system.In comparison with AlN ceramics,both bending strengthand fracture toughness of the composite materials are much bettered.Microstructuralobservation revealed that a lot of epitaxial growth fibrous AlN polytype occurred inmatrix.Y2O3 seems to act as a densifier for in-situ formation materials and as mediumfor growth of fibrous polytype.SiO2 is the growth promoter for fibrous polytype.Theoccurrnce of fibrous polytype may increase the strength and toughness of AlN ceramiccomposite mateirals. | LI Zonghuai CHEN Shengqi ZHOU Yanchun XIA Fei Institute of Metal Research,Academia Sinica,Shenyang,China Professor,Institute of Metal Research,Academia Sinica,Shenyang 110015,China | 1993 | Acta Metallurgica Sinica(English Letters)1993，6，7： | 0 |
| 4 | A CFD-Aided Galerkin Method for Global Linear Instability Analysis显示文摘Global linear instability analysis is a powerful tool for the complex flow diagnosis.However,the methods used in the past would generally suffer from some dis-advantages,either the excessive computational resources for the low-order methods or the tedious mathematical derivations for the high-order methods.The present work proposed a CFD-aided Galerkin methodology which combines the merits from both the low-order and high-order methods,where the expansion on proper basis func-tions is preserved to ensure a small matrix size,while the differentials,incompressibility constraints and boundary conditions are realized by applying the low-order linearized Navier-Stokes equation solvers on the basis functions on a fine grid.Several test cases have shown that the new method can get satisfactory results for one-dimensional,two-dimensional and three-dimensional flow problems and also for the problems with complex geometries and boundary conditions. | Shengqi Zhang Zhenhua Xia Shiyi Chen | 2021 | Communications in Computational Physics2021，29，1： | 0 |
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