Papers by Author: You Bin Wang

Abstract: The effect of aging on the corrosion property of Al-7Si-0.3Mg Alloy immersed in 3.5% NaCl solution was studied by Tafel polarization curves and corrosion weight loss measurement in this paper. The Vickers hardness of the alloy during aging was measured on Zwick hardness testing machine. The electrochemical behavior of the Al-7Si-0.3Mg alloys after the under aged, peak aged and over aged were analyzed, respectively. The results show that the hardness of the alloy increases at first with the increasing of aging time and gets to the maximum at 4 hour, and descends gradually with the aging time (over aged). Icorr under peak aged status get to the highest value and to the lowest one during under aged status. Correspondingly, corrosion properties under peak aged status are the worst case and the best with under aged status.

Abstract: Solid-state phase transformation has an important influence on mechanical property of Zn alloy with high Al content. The dynamic microstructure evolution of eutectoid transformation for the Zn alloy with high Al content was observed by high temperature metallography microscope. The phase of the Zn alloy with high aluminum at 300°C was analyzed by the high temperature X-ray diffractograms. The results show that eutectoid transformation originates in the grain boundary and develops rapidly as the heating temperature rises.The variation of eutectoid transformation completion with the time increasing in the dynamics process can be expressed by M=100(1-e^{-0.0023t1.3137})

Abstract: The corrosion property of three currently used hot dipped alloys (Al-8Si, Zn-0.6Ni and 55Al-Zn-Si) immersed in 3.5% NaCl solution were studied by analyzing the open circuit potential variation with time and electrochemical impedance spectroscopy (EIS) tests. The open circuit potential of the Al-8Si alloy is 100mV higher than the potential of Zn-0.6Ni and 55Al-Zn-Si, and the potential of Zn-0.6Ni is approach to the 55Al-Zn-Si alloy. The phase angles of the Al-8Si, 55Al-Zn-Si and Zn-0.6Ni are close to -80°,-70°,-60°, and the high impedance values at low frequencies are 105,104,103 Ω cm2, respectively. The EIS spectra of the alloys indicated two relaxation time constants. An “equivalent circuit” with the circuit elements representing the electrochemical properties was proposed to simulate the EIS spectra, and the simulated dates were in a good agreement with the experiment dates. The polarization resistance (Rp) of Al-8Si, 55Al-Zn-Si and Zn-0.6Ni are 18000, 2010, 251 Ω•cm-2, respectively. The results showed that the corrosion property of Al-8Si is well than the other alloys in the test solution.

Abstract: The effects of Mn addition on the microstructure and hardness of 6061 aluminum alloy were studied by means of scanning electron microscope (SEM) , energy dispersive X-Ray Analysis (EDX), X-ray diffraction (XRD) and hardness tester in this work. The results shows that rod and fishbone AlSiFeMn phase will be formed in the alloy with Mn addition in 6061 aluminium alloy, and the AlSiFeMn phase increases with the increasing of Mn content . By the mean of XRD, the Al4.07 Mn Si0.74 phase is found in the 6061 aluminium alloy from 0.7% to 1.5% Mn. The hardness increases with the increasing of Mn contents both for as-cast and for T6 heat treatment. However, the hardness growth rate for as-cast is much more than that for T6 heat treatment at the same Mn addition in the 6061 alloy. Mn has a little effect on the hardness for T6 heat treatment in 6061 alloy.

Abstract: Small amounts of Mn have been used in order to modify the microstructure and thus improve the properties of the alloys. The effect of Mn addition on structure and properties of cold rolled Al-Mg-Si-Cu alloy at different annealed temperatures is presented in this paper. Both recrystallization temperature and activation energy of recrystallization are obtained from the hardness-temperature curves. The results show that Mn can have an inhibitive effect on recrystallization. Within a certain concentration of Mn in the alloy (<0.7 wt.%) both the activation energy of recrystallization and recrystallization start temperature increase with the addition of Mn content. The activation energy of recrystallization of the alloy which contains 0 wt.% Mn, 0.3 wt.% Mn and 0.7 wt.% Mn are respectively 134.4 kJ·mol-1, 137.4 kJ·mol-1 and 140.1 kJ·mol-1 and the recrystallization start temperature increases from 190 to 230 as Mn content increases from 0 to 0.7 wt.%.