Time filter

Source Type

Hu X.,Nanchang University | Chen W.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation LTD | Wu B.,Nanchang University
Materials Science and Engineering A | Year: 2012

Cu 6Sn 5 fiber reinforced Sn in situ composites with a nominal composition Sn-1Cu (wt%) were produced by specially controlled directional solidification using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. The microstructure of as-produced composites was characterized by using optical microscopy (OM), electron microscopy (SEM) and microanalysis (EDX). The tensile strength and plasticity at room temperature were examined by tensile tests. The microstructure observation showed that the microstructure consisted of Β-Sn matrix and fiber-like Cu 6Sn 5 intermetallics compounds (IMCs). For a constant temperature gradient (12Kmm -1), it was found that the spacing between Cu 6Sn 5 fibers and diameter of single crystalline Cu 6Sn 5 fiber were mainly controlled by the solidification rate (V), and both of them decreased with increasing solidification rate. The strength was dominated by the Cu 6Sn 5 fiber alignment, such as the spacing and diameter. Thus the tensile tests results have been correlated to fiber spacing (λ) and diameter (d), since fiber growth has prevailed along all obtained Sn-1Cu samples. It was found that the ultimate tensile strength (UTS) and yield tensile stress (YS) initially increased with increasing solidification rate which ranged from 5 to 60μms -1, and decreased with further increasing solidification rate, such as 100μms -1. In contrast, the elongation (EL) decreased with increasing solidification rate due to the increased amount Cu 6Sn 5 IMC quantity. © 2012 Elsevier B.V.

Wu X.-B.,Tongji University | Liao J.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation LTD | Wang Z.-C.,Tongji University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

Water wave optimization (WWO) is a novel evolutionary algorithm borrowing ideas from shallow water wave models for global optimization problems. This paper presents a first study on WWO for a combinatorial optimization problem — the traveling salesman problem (TSP). We adapt the operators in the originalWWOso as to effectively exploring in a discrete solution space. The results of simulation experiments on a set of test instances from TSPLIB show that the proposed WWO algorithm is not only applicable and efficient for TSP, but also has significant performance advantage in comparison with two other methods, genetic algorithm (GA) and biogeography-based optimization (BBO). © Springer International Publishing Switzerland 2015.

Hu X.,Nanchang University | Chen W.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation LTD | Yu X.,Nanchang University | Li Y.,Nanchang University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

The effects of displacement rate and reflow duration on the shear strengths of the Cu/Sn37Pb/Cu soldered joints as well as the interfacial microstructure were investigated after reflowing. The samples were reflowed at 300 C for different durations (5 min, 15 min and 30 min) and then shear tested with different displacement rates ranging from 2.5 × 10-3 to 5 × 10-2 mm s-1. The intermetallic compounds (IMCs), including Cu6Sn5 and Cu3Sn phases were observed between Sn37Pb solder and Cu substrate, and their thicknesses increased with increasing reflow duration up to 30 min. The single lap shear test results indicated that the shear forces of the joints increased with increasing displacement rate, but decreased with increasing reflow duration. Failure mechanisms of soldered joints in different displacement rate regimes were investigated based on the fractography analysis. After reflowing for 5 and 15 min, the fractures of the Sn37Pb soldered joints mainly occurred inside the bulk solder irrespective of the displacement rate. While some broken Cu 6Sn5 particles could be observed at the bottom of dimples in solder bulk as the high displacement rates were adopted (such as 1 × 10-2 and 5 × 10-2 mm s-1). In case of reflow duration of 30 min, as the low displacement rates (such as 2.5 × 10-3 and 5 × 10-3 mm s-1) were adopted, the fracture patterns of soldered joints were similar to that of soldered joints reflowed for 5 and 15 min. In contrast, little solder and many IMCs were detected on the fracture surface under high displacement rates condition (such as 1 × 10-2 and 5 × 10-2 mm s-1), which indicated that the fracture mainly occurred in the interior of Cu-Sn IMC layer. The displacement rate sensitivities of the soldered joints reflowed for different durations were also investigated, and it is found that the displacement rate sensitivity decreased with increasing reflow duration due to the increased interfacial IMC layer thickness. © 2014 Elsevier B.V. All rights reserved.

Xiong Y.,Jiangxi Science and Technology Normal University | Wang H.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation LTD | Li Y.,Jiangxi Science and Technology Normal University
Lecture Notes in Electrical Engineering | Year: 2014

People's increasing demand formobile multimedia business, mobile communication must integrate the Internet to offer high-speed and high-quality mobile multimedia communication business. In the process of integration, the multimedia technology that has maturely developed in the Internet will play a very important role. This paper introduces the concepts and features of the multimedia technology. Through the research on the application of the four key technologies in multimedia technology in the field of mobile communication and detailed analysis of the advantages of 4G network and the impact that it has on the multimedia technology in the mobile communication field, prospect the development of themultimedia technology in the mobile communication. © Springer-Verlag Berlin Heidelberg 2014.

Cao Z.,Shanghai JiaoTong University | Wang F.,Shanghai JiaoTong University | Wan Q.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation LTD | Zhang Z.,Shanghai JiaoTong University | And 2 more authors.
Materials and Design | Year: 2015

Flow forming is a plastic deformation process to produce thin-walled and high-precision cylindrical components. In this study, the hot flow forming of Mg-8.5Al-0.5Zn-0.2Mn (AZ80) alloy tubes was conducted innovatively. The effects of processing parameters including flow forming temperature, spindle speed, feed ratio and thickness reduction on the microstructures and mechanical properties of AZ80 alloy tubes were investigated. The results show that a more unanimous and raised grain size appeared with deforming temperature from 300 to 420. °C. The variation of spindle speed and feed ratio had a slight influence on the microstructure, but an obvious influence on the tensile properties, particularly the elongation. With increasing the thickness reduction, the grain size decreased while the micro-hardness increased significantly. The electron backscatter diffraction (EBSD) results show that the c-axes of most grains are approximately parallel to the radial direction. And likewise, they have a slight deflection towards the axial direction. Furthermore, ultimate tensile strength (UTS) of 308. MPa and elongation of 9.8% were obtained when the hot flow forming was carried out under a temperature of 420. °C, a spindle speed of 400. rev/min, a feed ratio of 0.1. mm/rev and a thickness reduction of 45%. © 2014 Elsevier Ltd.

Discover hidden collaborations