Effects of trace addition of Ag on the fatigue crack propagation behavior and microstructure of a mediumstrength aged AI-Zn-Mg alloy were investigated in the present work. The results show that a combination of enhanc...Effects of trace addition of Ag on the fatigue crack propagation behavior and microstructure of a mediumstrength aged AI-Zn-Mg alloy were investigated in the present work. The results show that a combination of enhanced tensile strength and improved fatigue crack propagation resistance in Al-Zn-Mg alloys is achieved with small addition of Ag. The enhanced strength is attributed to the high density of η＇ precip- itates within the grains and narrow precipitate free zones in the vicinity of grain boundaries. The main contribution to the improvement of fatigue crack propagation resistance comes from the coarser precipitates within the grains. When subjected to two-step aging. Ag-added alloy shows larger semi-coherent matrix precipitates. These relatively coarser precipitates increase the homogeneity of deformation and therefore improve the fatigue crack propagation resistance. In addition, microstructure analysis indicates that the size and distribution of inclusions as well as the grain structures of Al-Zn-Mg alloys are independent of Ag addition.展开更多
Silver nanoparticles （AgNPs） were synthesised using equimolar concentrations of redtlcing agent vitamin C and AgCl precursor by simple precipitation method. The synthesised AgNPs were characterised by X-ray diffract...Silver nanoparticles （AgNPs） were synthesised using equimolar concentrations of redtlcing agent vitamin C and AgCl precursor by simple precipitation method. The synthesised AgNPs were characterised by X-ray diffraction （XRD）, UV-Visible, photoluminescence and field emission scanning electron microscopy （FESEM） analysis. The formation of AgNPs was confirmed by the typical surface plasmon resonance band at 426 nm. The presence of elemental silver and pure crystalline face centre cubic （fcc） structure was confirmed by energy dispersive X-ray analysis and XRD analysis, respectively. The FESEM images showed the formation of spherical AgNPs for lower concentrations （0.1 and 0.3 mol/L） while spike and flower shaped particles were formed for higher concentration. Photoluminescence characteristic band was observed with no shift at 390 nm indicating the stable nature of AgNPs. The antibacterial property of the AgNPs was tested against gram negative bacteria Pseudomonas aeruginosa by using Cissus quadrangular as a control and the result showed that vitamin C reduced AgNPs have good antibacterial activity.展开更多
基金financially supported by the National Key Research and Development Program of China (No. 2016YFB0300900)the National Natural Science Foundation of China (No. 51171209)
文摘Effects of trace addition of Ag on the fatigue crack propagation behavior and microstructure of a mediumstrength aged AI-Zn-Mg alloy were investigated in the present work. The results show that a combination of enhanced tensile strength and improved fatigue crack propagation resistance in Al-Zn-Mg alloys is achieved with small addition of Ag. The enhanced strength is attributed to the high density of η＇ precip- itates within the grains and narrow precipitate free zones in the vicinity of grain boundaries. The main contribution to the improvement of fatigue crack propagation resistance comes from the coarser precipitates within the grains. When subjected to two-step aging. Ag-added alloy shows larger semi-coherent matrix precipitates. These relatively coarser precipitates increase the homogeneity of deformation and therefore improve the fatigue crack propagation resistance. In addition, microstructure analysis indicates that the size and distribution of inclusions as well as the grain structures of Al-Zn-Mg alloys are independent of Ag addition.
基金DST-FIST and UGC-SAP,New Delhi for providing financial support to the Department of Physics,Manonmaniam Sundaranar UniversityNational Centre for Nanosciences and Nanotechnology(NCNSNT)University of Madras for providing FESEM and EDAX facilities
文摘Silver nanoparticles （AgNPs） were synthesised using equimolar concentrations of redtlcing agent vitamin C and AgCl precursor by simple precipitation method. The synthesised AgNPs were characterised by X-ray diffraction （XRD）, UV-Visible, photoluminescence and field emission scanning electron microscopy （FESEM） analysis. The formation of AgNPs was confirmed by the typical surface plasmon resonance band at 426 nm. The presence of elemental silver and pure crystalline face centre cubic （fcc） structure was confirmed by energy dispersive X-ray analysis and XRD analysis, respectively. The FESEM images showed the formation of spherical AgNPs for lower concentrations （0.1 and 0.3 mol/L） while spike and flower shaped particles were formed for higher concentration. Photoluminescence characteristic band was observed with no shift at 390 nm indicating the stable nature of AgNPs. The antibacterial property of the AgNPs was tested against gram negative bacteria Pseudomonas aeruginosa by using Cissus quadrangular as a control and the result showed that vitamin C reduced AgNPs have good antibacterial activity.
