The effects of trace elements Cd and Sn on precipitation process of Al-Si-Cu-Mg cast alloys were investigated in the present research.It is shown that the addition of Cd and Sn not only increases remarkably the aging ...The effects of trace elements Cd and Sn on precipitation process of Al-Si-Cu-Mg cast alloys were investigated in the present research.It is shown that the addition of Cd and Sn not only increases remarkably the aging peak hardness and reduces the time to reach aging peak,but also eliminates the double-aging-peak phenomenon which appears in Al-Si-Cu-Mg alloys.In Al-Si-Cu-Mg alloys the first aging peak corresponds to GP zones(especially GPⅡ) ,and the second one is caused by metastable phases.The obvious time interval of transition from GPⅡ to metastable phases associates with the double-aging-peak phenomenon.The results of DSC and TEM show that Cd/Sn elements suppress the formation of GPⅠzone,stimulate the formation of θ",θ' and θ phases,and then shorten remarkably the temperature intervals of each exothermic peak.Because the transition interval between GPⅡzone and metastable phases is shortened by Cd/Sn in Al-Si-Cu-Mg cast alloys,θ' phase coexists with θ" phase in matrix of ageing peak condition,which causes effective hardening on the alloys,and at the same time,eliminates the double-aging-peak phenomenon.展开更多
The diversity of interface morphologies is observed for directionally solidified Sn-0.65%Cd alloy under a travelling magnetic field （TMF） in the 4 mm-diameter sample. Under an upward TMF, planar and cellular interfa...The diversity of interface morphologies is observed for directionally solidified Sn-0.65%Cd alloy under a travelling magnetic field （TMF） in the 4 mm-diameter sample. Under an upward TMF, planar and cellular interface morphologies transform alternately with increasing magnetic flux density （B≤10.3 mT）. The interface morphology transforms from shallow cellular to deep cellular morphology under a weak downward TMF （B=3.2 mT）. When the magnetic flux density increases further, both sides of the interface morphology appear to be slightly inconsistent, but they roughly tend to be planar under a strong downward TMF （BS10.3 mT）. The interface instability may be attributed to the flow driven by the TMF. Moreover, the shape of interface appears to be almost flat under an upward TMF, but deflective under a downward TMF.展开更多
Ternary Pb-Sn-Cd alloy nanoparticles were prepared b y the sonochemical dispersion method. The nanoparticles were found to be about 40 —60 nm and coated with an amorphous layer of surfactant dioctadecyldithiophosph a...Ternary Pb-Sn-Cd alloy nanoparticles were prepared b y the sonochemical dispersion method. The nanoparticles were found to be about 40 —60 nm and coated with an amorphous layer of surfactant dioctadecyldithiophosph ate(DDP).The formation and constituent of the as-prepared nanoalloy were charac terized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), differential thermal anal ysis and thermogravimetry (DTA-TG), and Fourier transform infrared (FT-IR) spe ctrophotometer.It was also found that the powder showed excellent antiwear prope rty by tribological test results.展开更多
文摘The effects of trace elements Cd and Sn on precipitation process of Al-Si-Cu-Mg cast alloys were investigated in the present research.It is shown that the addition of Cd and Sn not only increases remarkably the aging peak hardness and reduces the time to reach aging peak,but also eliminates the double-aging-peak phenomenon which appears in Al-Si-Cu-Mg alloys.In Al-Si-Cu-Mg alloys the first aging peak corresponds to GP zones(especially GPⅡ) ,and the second one is caused by metastable phases.The obvious time interval of transition from GPⅡ to metastable phases associates with the double-aging-peak phenomenon.The results of DSC and TEM show that Cd/Sn elements suppress the formation of GPⅠzone,stimulate the formation of θ",θ' and θ phases,and then shorten remarkably the temperature intervals of each exothermic peak.Because the transition interval between GPⅡzone and metastable phases is shortened by Cd/Sn in Al-Si-Cu-Mg cast alloys,θ' phase coexists with θ" phase in matrix of ageing peak condition,which causes effective hardening on the alloys,and at the same time,eliminates the double-aging-peak phenomenon.
基金Project(50774061) supported by the National Natural Science Foundation of ChinaProject(28-TP-2009) supported by the Research Fund of State Key Laboratory of Solidification Processing(NWPU),China
文摘The diversity of interface morphologies is observed for directionally solidified Sn-0.65%Cd alloy under a travelling magnetic field （TMF） in the 4 mm-diameter sample. Under an upward TMF, planar and cellular interface morphologies transform alternately with increasing magnetic flux density （B≤10.3 mT）. The interface morphology transforms from shallow cellular to deep cellular morphology under a weak downward TMF （B=3.2 mT）. When the magnetic flux density increases further, both sides of the interface morphology appear to be slightly inconsistent, but they roughly tend to be planar under a strong downward TMF （BS10.3 mT）. The interface instability may be attributed to the flow driven by the TMF. Moreover, the shape of interface appears to be almost flat under an upward TMF, but deflective under a downward TMF.
文摘Ternary Pb-Sn-Cd alloy nanoparticles were prepared b y the sonochemical dispersion method. The nanoparticles were found to be about 40 —60 nm and coated with an amorphous layer of surfactant dioctadecyldithiophosph ate(DDP).The formation and constituent of the as-prepared nanoalloy were charac terized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), differential thermal anal ysis and thermogravimetry (DTA-TG), and Fourier transform infrared (FT-IR) spe ctrophotometer.It was also found that the powder showed excellent antiwear prope rty by tribological test results.
