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Zhang X.B.,Nanjing Institute of Technology | Zhang X.B.,Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology | Sun W.,Nanjing Institute of Technology | Sun W.,Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology | And 5 more authors.
Materials Research Innovations | Year: 2015

Mg-(4-x)Nd-x Gd-0·3Sr-0·2Zn-0·4Zr (wt.-%, x=0, 1, 2, and 3) alloys with various Gd/Nd ratios were prepared by gravity casting, solution-treated and then hot extruded. The microstructures, mechanical properties at room temperature, corrosion behaviour in simulated body fluid of the as-extruded alloys were studied. The as-extruded alloys undergo partially dynamic recrystallisation, and the equiaxed grains become coarse with increasing Gd/Nd ratio. The strength of the alloys increases first and then decreases with increasing the Gd/Nd ratio; however, the elongation of the alloys increases apparently with increasing Gd/Nd ratio. Both immersion test and polarisation test indicate that the corrosion rate of the as-extruded alloys is reduced with increasing the Gd/Nd ratio, and the alloys exhibit relatively uniform corrosion morphologies. © W. S. Maney & Son Ltd 2015. Source


Ba Z.,Nanjing Institute of Technology | Ba Z.,Jiangsu Province Advanced Structural Materials and Application Technology Laboratory | Zhang X.,Nanjing Institute of Technology | Zhang X.,Jiangsu Province Advanced Structural Materials and Application Technology Laboratory | And 4 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2015

The hydrotalcite (Mg6Al2(OH)16CO3·4H2O) film was prepared on magnesium alloy by ultrasonic wave, and the effect of power and frequency of ultrasonic wave on its microstructure and corrosion resistance was also investigated. The surface morphology and phase composition were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), respectively. The polarization curve and electrochemical impedance spectroscopy (EIS) were applied to evaluate the anti-corrosion performance. The results show that the film formation can be significantly accelerated by ultrasonic-assisted treatment. The film forming rate increases with the ultrasonic power and frequency, while the quality of film will be deteriorated through overwork. When the ultrasonic power and frequency was 100 W and 80 kHz, respectively, a thicker and integrated layer was formed on the magnesium alloy. Its corrosion resistance was superior to that of the bare magnesium alloy, and the corrosion current density was approximately 1/20 that of the substrate. © 2015, Chongqing Functional Materials Periodical Press Co. Ltd. All right reserved. Source


Fang X.-X.,Nanjing Institute of Technology | Zhang X.-B.,Nanjing Institute of Technology | Wang Q.,Jiangsu Konsung Equipment Co. | Ba Z.-X.,Nanjing Institute of Technology | Wang Z.-Z.,Nanjing Institute of Technology
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2014

The NaMgF3 films on the surface of Mg-Nd-Zn-Zr magnesium alloy were fabricated by immersion method. Their corrosion properties were valuated by dripping test, electrochemical test and immersion method, respectively. The microstructures of the original and corrosive samples were observed by SEM and their chemical compositions were analyzed by EDS. The results show that the size of NaMgF3 particle is obviously reduced with the increase of conversion treatment temperature; however, it is little affected by the conversion treatment time. The NaMgF3 particles grow by two-dimensional nucleation, step growth mechanism and screw growth mechanism. The average hydrogen evolution rate of Mg-Nd-Zn-Zr magnesium alloy in simulated body fluid (SBF) solution can be significantly decreased by NaMgF3 film. The NaMgF3 films gradually transform into a new film consisting of fluoride and phosphate in the SBF solution, which will continue to protect the magnesium alloy from the corrosion. Source


Zhang X.B.,Nanjing Institute of Technology | He X.C.,Nanjing Institute of Technology | Xue Y.J.,Nanjing Institute of Technology | Wang Z.Z.,Nanjing Institute of Technology | Wang Q.,Jiangsu Konsung Equipment Co.
Corrosion Engineering Science and Technology | Year: 2014

Mg-2·2Nd-xSr-0·3Zr alloys (wt-%, x50, 0·4, 0·7 and 2·0) were prepared by gravity casting to study the effects of Sr addition on the microstructure and corrosion resistance of Mg-Nd-Zr alloys in simulated body fluid (SBF). Phases were identified by X-ray diffraction, and microstructure was observed with optical microscopy and scanning electron microscopy. Corrosion resistance of the alloys was determined by evaluating mass loss and hydrogen evolution during immersion in SBF. Mg17Sr 2 phase was formed, and the grain size decreased with additional Sr addition. For the grain refinement and more continuous second phase, which could improve the corrosion resistance, the alloy with 0?7 wt-%Sr showed the slowest corrosion rate, whereas the alloy with 2?0 wt-% showed the fastest corrosion rate due to the increased volume fraction of Mg17Sr2, which led to severe local microgalvanic corrosion. Source


Zhang X.B.,Nanjing Institute of Technology | He X.C.,Nanjing Institute of Technology | Xue Y.J.,Nanjing Institute of Technology | Wang Z.Z.,Nanjing Institute of Technology | Wang Q.,Jiangsu Konsung Equipment Co.
Materials Technology | Year: 2014

Mg-(4-x)Nd-xGd-0?3Sr-0?2Zn-0?4Zr (wt-%, x50, 1, 2 and 3) alloys were prepared by gravity casting. Microstructure was analysed by X-ray diffraction, optical microscopy and scanning electron microscopy respectively. The a-Mg and Mg41Nd5 phases existed in the as cast alloys with 4% and 3% Nd addition, while the new Mg3Gd was found in the alloys with 3% Gd addition. The volume fraction of the second phase reduced with increasing Gd addition and the microstructure was refined by the Gd addition. The corrosion resistance of the alloys was evaluated by mass loss, hydrogen evolution and Tafel polarisation tests. The results showed that the corrosion rate of the alloys decreased with increasing Gd addition even though the corrosion rates of the alloys obtained by different methods showed different values. Moreover, the corrosion morphologies of the alloys were uniform. © 2014 W. S. Maney and Son Ltd. Source

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