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Peng K.-P.,Fuzhou UniversityFujian | Mou X.-P.,Fujian Inspection and Research Institute for Product Quality | Ma Y.-S.,Fujian Qianda Heavy Machinery Co LtdFujian
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2014

Cu-35Zn alloy deformed by constrained groove pressing (CGP) up to 10 passes and 30% cold rolling was annealed at different temperatures. The thermal stability of Cu-35Zn processed by CGP and cold rolling was studied. The results show that the grains of Cu-35Zn alloy are refined by CGP and cold rolling. After the deformation of CGP and cold rolling, the hardness and strength of the samples are improved. The recovery process of specimens deformed by CGP and cold rolling is dominants when annealing below 200 ℃. The crystallites with large angle grain boundary are formed at 220 ℃. The recrystallization and grain growth are completed at 300-400 ℃. Source


He S.-H.,CAS Fujian Institute of Research on the Structure of Matter | He S.-H.,Fuzhou UniversityFujian | Liu P.-F.,CAS Fujian Institute of Research on the Structure of Matter | Liu P.-F.,University of Chinese Academy of Sciences | And 6 more authors.
Acta Materialia | Year: 2015

Lead-free In4Se3 is a newly established promising middle temperature n-type thermoelectric (TE) material candidate. Series of Yb-substituted In4-xYbxSe3 (x = 0.01-0.09) samples are prepared herein and their TE properties and the structure-property relationship are investigated. Magnetic molar susceptibility measurements indicate that Yb is nonmagnetic. However, the Yb doped samples behave abnormally in transport properties. The unit cell volume variations and the carrier concentration (ne) changes reveal that Yb substitutes the In4+ site when x < 0.05 in the unitcell of In4Se3 and behaves in transport property as an +1 ion leading to a slow ne decrease; differently, Yb substitutes the In35+ sites in the unitcell of In4Se3 when x > 0.05, and behaves as an acceptor leading to a sharp ne decline. These are considered to be attributed to the Fermi level pinning of the f and d orbitals of Yb. Such Yb substitution preference is also supported by our primary formation energy calculation. Besides, the carriers that on the pinning level are highly localized, thus contribute very little to the electrical conductivity, but contribute to some degree to the thermal conductivity as shown by property-temperature plots. In addition, the Yb atoms produce resonate states around EF that enhance the Seebeck coefficient. As a heavy atom, Yb effectively scatter phonons resulting in the thermal conductivity reduction. All these factors together give In3.95Yb0.05Se3 a significant 30% ZT at 703 K relevant to that of the pure In4Se3. © 2015 Acta Materialia Inc. All rights reserved. Source


Xu H.,Fuzhou UniversityFujian | Xu H.,Fujian University of Traditional Chinese Medicine | Zhu X.,Fujian Agriculture and forestry University | Dong Y.,Fuzhou UniversityFujian | And 3 more authors.
Sensors and Actuators, B: Chemical | Year: 2016

Graphite carbon nitride nanosheets (g-C3N4 NSs) are the promising metal-free polymer-like semiconductor nanomaterials, which exhibit excellent electrochemiluminescence (ECL) behavior. The g-C3N4 NSs modified the glass carbon electrode showed the obvious ECL response using 10 mM S2O8 2− as the co-reactant at the scan rate of 0.1 V/s. The presence of Cu2+ would quench ECL emission due to the photo induced electron transfer (PET). Pyrophosphate anion (PPi), an important anion in several bioenergetics and metabolic processes, can chelate with Cu2+ with a strong affinity. The introduction of PPi could release Cu2+ from Cu2+-g-C3N4 NSs system, resulting in the ECL recovery. The dosage of Cu2+ and the ECL recover time were further investigated. Under the optimized condition PPi can be detected in the range of 2.0–800 nM with the detection limit of 75 pM based on 3ơ/slope. This ECL sensor also possessed good selectivity to PPi, and has been used to detect PPi in the synovial fluid. © 2016 Elsevier B.V. Source


Wang B.,Fuzhou UniversityFujian | Deng L.,Fuzhou UniversityFujian | Adrien C.,Chongqing University | Guo N.,Chongqing University | And 2 more authors.
Materials Characterization | Year: 2015

The effects of initial texture on the flow behavior, microstructure and texture evolution of Mg-3Al-1Zn alloy hot rolled plate with a strong basal texture during tension at room temperature have been investigated by experiments and simulations. Three kinds of specimens were cut from this plate with their tensile directions aligned 0°, 45°, and 90° to the normal direction (ND), and they were referred as 0ND, 45ND and 90ND specimens, respectively. A crystal plasticity model was developed to demonstrate the relationship between textures and deformation modes. The results show that the general features of flow curves and texture evolutions of AZ31 alloy during tension can be well explained by the relative activities of deformation modes, which exhibit a pronounced orientation dependence on both the starting and current textures. The obvious yielding behaviors in 0ND and 45ND specimens are induced by the initial activity of {10-12} twinning, and the strain hardening behavior is related to the activities of {10-12} twinning, basal slip and prismatic slip. Due to the existence of {10-11} twinning at low strain, the elongation to rupture of 90ND specimen is much lower than those the elongation of 0ND and 45ND specimens. Although prismatic slip activity depends on the initial texture, its activities always increases during tension, affecting the flow curves, microstructure and texture evolutions. The high prismatic slip activities in 0ND and 90ND specimens result in a strong {10-10} prismatic texture, while the activity of pyramidal < c + a > slip is always negligible in all specimens and insensitive to the initial texture during tension. © 2015 Elsevier Inc. All rights reserved. Source


Huang F.,Tongji University | Huang F.,Fuzhou UniversityFujian | Huang F.,University of Nevada, Reno | Yu X.,Fuzhou UniversityFujian | And 3 more authors.
Thin-Walled Structures | Year: 2016

In general, the calculation of ultimate load capacity (UL) of a concrete-filled steel tubular (CFST) column is based on the assumption that the load is resisted by both the steel tube and the concrete core simultaneously as a composite member. However, steel tubes of CFST columns are preloaded due to self-weight, wet concrete weight as well as temporary construction loads before the composite action is formed. There is still no consensus on how the preload affects the loading resistance of CFST columns and how to quantify the effect of preload on the ultimate strength. The paper reported an experimental study on circular CFST columns subjected to preload. The testing results showed that the preloading effect increased with the increase of slenderness, decreased the ultimate load capacity and increased the deformation significantly at high preloading ratio, but did not have much influence on the ultimate load capacity at light preload. Then, a parametric analysis of coupled effects of preloading ratio with other parameters, such as slenderness ratio, eccentric ratio, as well as material properties, is presented. Finally, a simplified method is proposed to predict the ultimate load capacity of CFST columns with preload. The preloading reduction factor of simplified methods of UL based on regressive analysis can be used to evaluate the UL of CFST columns with preload after verified by overall comparison of total preloading tests. © 2015 Elsevier Ltd. All rights reserved. Source

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