2024-T6 Al alloy sheet s were modified by bis-[triethoxysilylpropyl] tetrasulfide
(BTESPT) silane film to improve the corrosion resistance. Fourier-Transform Reflection Absorption
(FTIR-RA) spectroscopy was used for structural characterization of BTESPT silane film formed on
surface of the sheet. Potentiodynamic polarization and immersion test in 3.5% NaCl solution were
used for evaluating the corrosion performances of the silane film. The results showed that the film
formed after curing at 120 °C for 40 min was cross-linked through Si-O-Si and that it was covered on
the entire surface of the sheet. The content of elements S and Si on the Al2CuMg particles is a little
higher that of on the matrix. The strong peak at 1032 cm-1 indicated that the film was linked to the
sheet by Si-O-Al. Compared to the untreated case, the corrosion current density of the sheet treated
with the silane film was reduced by close to 2 orders. Treatment of BTESPT silane can provide about
670 h protection of corrosion for the sheet in 3.5% NaCl water solution.
Mcrostructure and properties of Mg-Zn-Nd-Cd-Zr alloy have been investigated on different solution treatments and artificial aging conditions by optical microscope, SEM (scanning electron microscope) and TEM(transmission electron microscope). The results indicate that the grain boundarys become thinner and the second phases distributed on the grain boundarys become finer by double-stage homogenization at 400°C for 2h plus 460°C for 12h than that of homogenization at 420°C for 24h. Double-stage homogenization brings a greater peak-ageing hardness and longer time to reach peak hardness 20h about., and the ultimate tensile strength is 345MPa at 140°C for 34h, higher 15% than that of as-extruded
The deformation behavior and microstructure of 6069 aluminum alloy have been studied by isothermal compression at temperature ranging from 300°C to 450°C on Gleeble-1500 machine at strain rates from 0.01 to 10s-1. The results show that the deformation temperature and strain rate is essential to the flow characteristic, and the main deformation mechanism for 6069 aluminum alloy is dynamic recovery at low strain rates. The dynamic recrystallization take place at the strain rates of 10s-1 and deformation temperature ranges of 300~350°C. At constant strain rate, the flow stress and steady-state flow stress decrease with deformation temperature increasing. While at constant temperature, the flow stress and steady-state flow stress increase with increasing strain rate. The processing map at the strain of 0.7 is obtained and the map exhibits two safe deformation domains (300~350°C at 1~10s-1 and 380~450°C at 0.01~0.3s-1).
By using digital micro-hardness testing, mechanical testing, optical microscopy(OM), scanning electron microscopy(SEM), transimission electron microscopy(TEM), microstructure and mechanical properties of Mg-9Gd-3Y-xZn (x=0,1,2,3 wt.%) alloys during extrusion and following aging at 210 °C were investigated. The results showed that Zn can refined grains of the alloy. In T5 condition the average grains of the alloy without Zn addition were about 20.08 μm; the average grains of the alloys with 1 wt.% Zn addition and 3 wt.% Zn addition were about 15.26 μm and 10.17 μm, respectively. For the alloy with 1 wt.% Zn addition in peak-aged state, the values of tensile strength and yield strength reached 418MPa and 329 MPa, as well as ductility rate reached 5.6 %, respectively, exhibiting superior mechanical properties .
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