检索结果-南通市图书馆

A hot tearing criterion based on solidifcation microstructure in cast alloys

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第10期105卷 68-80页

作者： Bo Hu Zixin li dejiang li Tao Ying Xiaoqin Zeng Wenjiang Ding National Engineering Research Center of light Alloy Net Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China The State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China

A criterion based on solidifcation microstructure was proposed to precisely predict the hot tearing behavior of cast alloys,which takes into account the effects of both mechanical and nonmechanical *** criterion focuses on the events occurring at the grain boundary,which are determined by the thermal contraction,solidifcation shrinkage,grain growing and liquid *** criterion responds to a series of factors that affect hot tearing,such as alloy composition,mold design,casting process and *** credibility has been validated by studying the hot tearing behavior of Mg-Ce *** conformity with the experimental results,this criterion predicted decrease in the number of rods occurring hot tearing with increasing cerium content.A simplifed criterion was derived and validated by Mg-Ce(equiaxed grain)and Mg-Al(columnar grain)alloy systems,which is suitable for the case where the eutectic liquid fraction is low and the liquid feeding can be *** addition,a hot tearing index for equiaxed grains was proposed,that is,|d T/d(f_(s)^(1/3)near(f_(s))^(1/3)=1,and its prediction results were consistent with the hot tearing susceptibility calculated from the experimental results.

关键词： Hot tearing Microstructure Magnesium alloys Casting Criterion

Deformation mechanism and dynamic precipitation in a Mg-7Al-2Sn alloy processed by surface mechanical attrition treatment

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第7期35卷 1473-1478页

作者： Xiaoying Shi Yangxin li Xiaoqin Zeng Yong liu Bin Chen Jian Lu dejiang li National Engineering Research Center of light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite Shanghai Jiao Tong UniversityShanghai200240China Commercial Aircraft Engine Company limited Aero Engine Corporation of ChinaShanghai200241China Key Laboratory of Near Net Forming of Jiangxi Province Nanchang UniversityNanchang330031China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai200240 Department of Mechanical and Biomedical Engineering City University of Hong KongKow-loonHong Kong999077China

The effect of second phases on the deformation mechanism of as-cast, solution-treated and aged Mg-7Al-2Sn (AT72) alloys during surface mechanical attrition treatment (SMAT) was investigated. Twinning was suppressed in the alloys containing second phases, which can provide nonuniform microstructures and phase boundaries as dislocation sources. Dynamic precipitation in AT72 alloys was studied during SMAT deformation as ***2Sn particles can dynamically precipitate on the surface of all AT72 alloys during SMAT process. The quantity of Mg2Sn particles in the as-cast alloy, which is determined by the initial quantity of second phases, is larger than that of T4 and T6 alloys after the SMAT process.

关键词： Magnesium alloys Surface mechanical attrition treatment Deformation mechanism Dynamic precipitation

Fatigue Magnification Factors of Arc-Soft-Toe Bracket Joints

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2018年第3期17卷 527-534页

作者： FU Qiang li Huajun WANG Hongqing WANG shuqing li dejiang li Qun FANG Hui College of Engineering Ocean University of China Qingdao 266100 China CIMC RAFFLES Yantai 264000 China School of Aerospace Engineering Xi'an Jiaotong University Xi'an 710049 China

Arc-soft-toe bracket(ASTB), as a joint structure in the marine structure, is the hot spot with significant stress concentration, therefore, fatigue behavior of ASTBs is an important point of concern in their design. Since macroscopic geometric factors obviously influence the stress flaws in joints, the shapes and sizes of ASTBs should represent the stress distribution around cracks in the hot spots. In this paper, we introduce a geometric magnification factor for reflecting the macroscopic geometric effects of ASTB crack features and construct a 3D finite element model to simulate the distribution of stress intensity factor(SIF) at the crack endings. Sensitivity analyses with respect to the geometric ratio Ht/Lb, R/Lb, Lt/Lb are performed, and the relations between the geometric factor and these parameters are presented. A set of parametric equations with respect to the geometric magnification factor is obtained using a curve fitting technique. A nonlinear relationship exists between the SIF and the ratio of ASTB arm to toe length. When the ratio of ASTB arm to toe length reaches a marginal value, the SIF of crack at the ASTB toe is not influenced by ASTB geometric parameters. In addition, the arc shape of the ASTB slope edge can transform the stress flowing path, which significantly affects the SIF at the ASTB toe. A proper method to reduce stress concentration is setting a slope edge arc size equal to the ASTB arm length.

关键词： Arc-soft-toe bracket stress intensity factor geometric magnification factors

A Review of Magnesium Alloys as Structure–Function Integrated Materials

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1301-1338页

作者： Zhenfei Jiang Bo Hu Zixin li Fanjin Yao Jiaxuan Han dejiang li Xiaoqin Zeng Wenjiang Ding National Engineering Research Center of light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China

Magnesium alloys have a significant advantage,lower density over the other structure materials;hence,they have been widely used in various fields such as transportation and *** the development of research and the enlargement of the research scope,more advantages have been revealed:excellent shielding efficiency,extraordinarily high damping capacity,as well as impressive thermal ***,Mg alloys have the potential to be various functional materials,such as electromagnetic shielding material,damping material,and thermal conductive *** review comprehensively summarizes the research progress and the up-to-date summary of Mg alloys as structure–function integrated materials in recent *** atoms,heat treatment,deformation,secondary phase,and temperature,which have a significant influence on the properties of magnesium alloys,are *** expect this review to be helpful for those who are working on developing structure–function integrated materials with superior comprehensive performance.

关键词： Magnesium alloys Structure-function integrated Electromagnetic shielding Damping capacity Thermal conductivity

Microstructure and mechanical properties of Mg-4.0Zn alloy reinforced by NiO-coated CNTs

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2017年第5期33卷 452-460页

作者： Qiuhong Yuan Xiaoshu Zeng Yanchun Wang Lan Luo Yan Ding dejiang li Yong liu Department of Materials Processing and Engineering Nanchang UniversityNanchang 330031China Physical Science and Technology College Yichun UniversityYichun 336000JiangxiChina School of Materials Science and Engineering Nanchang UniversityNanchang 330031China National Engineering Research Center of ligh t Alloys Net Forming Shanghai Jiao Tong UniversityShanghai 200240China

Mg-4.0Zn alloy composite reinforced by NiO-coated CNTs （NiO@CNTs） was synthesized by combining ball-milling and a casting process. The yield strength （YS） and elongation to failure of the composite were dramatically increased by 44.9% and 38.6%, respectively, compared to its alloy counterpart. The signifi- cantly eahanced mechanical properties of the as-synthesized composite are mainly ascribed to an improved interracial bond, grain refinement and good dispersion of CNTs in the matrix via. coating NiO on CNTs. It is shown that the NiO-nanolayer on the CNTs significantly enhances the interfacial bonding strength and effectively prevents the agglomeration of CNTs. NiO@CNTs are, therefore, expected to be a highly sustainable and dispersible reinforcement for magnesium matrix composites with superior performance.

关键词： Magnesium alloy Carbon nanotubes NiO Composites Mechanical properties

Characterization on the formation of porosity and tensile properties prediction in die casting Mg alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2022年第7期10卷 1857-1867页

作者： Zixin li dejiang li Wenke Zhou Bo Hu Xingfeng Zhao Jingya Wang Ming Qin Jiangkun Xu Xiaoqin Zeng National Engineering Research Center of light Alloy Net Forming School of Materials Science and EngineeringShanghai Jiao Tong University800 Dongchuan RoadShanghai 200240China Hitachi(China)Research&Development Corporation Rui Jin BuildingNo.205 Maoming Road(S)Shanghai 200020China The State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University800 Dongchuan RoadShanghai 200240China

The 3D visualization of the porosity in high-pressure die casting(HPDC)Mg alloys AZ91D and Mg4Ce2Al0.5Mn(EA42)was investigated by X-ray computed *** was demonstrated that the volumetric porosity at the near-gate location for alloy EA42 was significantly higher than that far from the gate *** difference resulted from the low valid time during intensified casting pressure *** of alloy EA42 exhibited a narrow pore distribution in the side view(~0.5 mm)compared to the wide distribution(~1.8 mm)of alloy AZ91D,which was mainly attributed to the formation mechanism of the defect *** formation of microporosity in the defect band of alloy EA42 was inhibited because of the significant latent heat released by a large amount of the Al11Ce3phase segregated in the defect band during ***,an effective estimator(Z-Propagation)was introduced,which is proposed to predict the projected area fraction of the porosity(f)involved during tensile failure with better effectiveness compared with traditional methods based on the actual fractured *** coupling the Z-Propagation method with the critical local strain model,the logarithmic fracture strain and true fracture stress of the specimens were predicted within 3.03%and 1.65%of the absolute value of the average relative error(AARE),respectively.

关键词： High-pressure die casting Porosity Tensile property Magnesium alloy X-ray computed tomography

Microstructural evolution of Mg-Al-Re alloy reinforced with alumina fibers

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2020年第3期8卷 565-577页

作者： li li dejiang li Xiaoqin Zeng Alan A.Luo Bin Hu Anil K.Sachdev liangliang Gu Wenjiang Ding Shanghai Jiao Tong University ShanghaiChina The Ohio State University ColumbusOHUnited States General Motors China Science Lab ShanghaiChina General Motors Global R&D Center WarrenMIUnited States

Few studies were reported on the phases'relationships of AE44(Mg-4.0Al-4.1RE-0.3Mn,wt.%)and its *** this work,AE44 alloy and Saffil(6-Al2O3)/AE44 Metal matrix composite(MMC)were both prepared by slow shot high pressure die casting(SS-HPDC)technology and their phase constitutions were all studied in detail using experimental techniques combined with CALPHAD(Calculation of Phase Diagram)*** results revealed that the alloy consists of the a-Mg matrix,A1hRE3 intermetallic phase,and one trace phase AI3RE,while the composite contains five major phases:a-Mg,5-AI2O3,AI3RE,MgO and *** two trace phases of A12RE and AI11RE3,respectively.A1hRE3 is partly derived from ALRE,while A13RE is a product of the peritectoid reaction between the two *** presence of MgO and Mg2Si is due to the interfacial reaction between the SiO2 binder in the fiber preforms and the molten magnesium during *** use of SiO2 binder in the preform manufacturing was limited/minimized to reduce the MgO formation in the MMC casting process,which can be detrimental to the fatigue performance of the MMC materials.

关键词： Mg-Al-RE Magnesium composite Slow shot high pressure die casting Microstructure CALPHAD AlxREy

Post-fire residual service performance of magnesium alloys reinforced by rare earths

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第12期42卷 2374-2384页

作者： Jiaxuan Han Bo Hu Zhenfei Jiang Mingdi Yu Fanjin Yao Zixin li Bensong Chen Wanzhang Yang dejiang li Xiaoqin Zeng Wenjiang Ding National Engineering Research Center of light Alloy Net Forming and the State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Yunnan Aluminium Co. Ltd.

The flammability of magnesium alloys continues to be a significant barrier to their extensive application,and alloying with rare earth elements（REs） is an effective way to enhance the ignition and fire resistance of Mg alloys. Three commercial as-extruded Mg alloys（AZ80 and two Mg-RE alloys: EZ30K and WE43）were directly exposed to flame heating for revealing the evolutions of microstructure and mechanical properties, which is valuable in assessing the post-fire residual service performance of Mg alloy components. Results show that secondary phase dissolution, grain growth, grain boundary melting, alloy melting, and defects generation successively occur during the heating process. After short-term heating for 30 s, the elongation of AZ80 alloy increases significantly by 214%, from 3.82% to 12.01%, with minimal change in strength compared to the initial unheated state. This transformation is attributed to the recovery, grain growth, Mg17Al12dissolution and dislocation density reduction. Conversely, EZ30K and WE43 alloys exhibit minimal changes in mechanical properties after short-term heating for 60 s,attributed to the pinning effect of REs. However, in subsequent heating states, resolidified microstructure and the presence of defects lead to a noteworthy decrease in both strength and elongation. Among these three alloys, the fire resistance follows this ranking: EZ30K > WE43 > AZ80, primarily due to the high thermal conductivity of EZ30K alloy and the thermal stability improved by the addition of REs.

关键词： Magnesium alloys Rare earths Fire Residual service performance Microstructure Mechanical properties

Basal-plane stacking-fault energies of Mg alloys: A first-principles study of metallic alloying effects

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第10期34卷 1773-1780页

作者： Qing Dong Zhe Luo Hong Zhu Leyun Wang Tao Ying Zhaohui Jin dejiang li Wenjiang Ding Xiaoqin Zeng National Engineering Research Center of light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite School of Materials Science and Engineering Shanghai Jiao Tong Universit University of Michigan–Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong University

Generalized stacking-fault energies （GSFEs） of basal-plane stacking faults 11 and 12 in Mg alloys have been studied based on first-principles calculations, where 43 alloying elements were considered. It is found that the most contributing features of alloying elements to GSFEs are bulk modulus, equilibrium volume, binding energy, atomic radius and ionization energy. Both bulk modulus and ionization energy exhibit positive relationships with GSFEs, and the others show opposite relationships. Multiple regressions have been performed to offer a quantitative prediction for basal-plane GSFEs in Mg-X systems. GSFEs, alloying effects of elements and the prediction model established within this work may provide guidelines for new Mg alloys design with better ductility.

关键词： First-principles calculations Magnesium alloys Stacking-fault energy Alloying effect