The effects of Hg and Ga on the electrochemical corrosion behavior of Mg-5%Hg (molar fraction) alloys were investigated by the measurement of polarization curves and galvanostatic test. The microstructure of the alloy...The effects of Hg and Ga on the electrochemical corrosion behavior of Mg-5%Hg (molar fraction) alloys were investigated by the measurement of polarization curves and galvanostatic test. The microstructure of the alloys and the corroded surface of the specimens were investigated by scanning electron microscopy, X-ray diffractometry and emission spectrum analysis. It can be concluded that the addition of 1%Ga (molar fraction) reduces corrosion current density from 26.98 mA/cm2 to 2.34 mA/cm2; while the addition of 1%Hg (molar fraction) increases corrosion current density. The addition of Ga and Hg both promotes the electrochemical activity of the alloys and the influence of Ga is more effective than Hg. Mg-5%Hg-1%Ga alloy has the best electrochemical activity, showing mean potential of -1.992 V. The activation mechanism of the magnesium alloy produced by Hg and Ga was put forward. Magnesium atoms are dissolved in liquid Hg and Ga to form amalgam and undergo severe oxidation at the amalgam/electrolyte interface.展开更多
The regulation of ceramic coating formed by micro-arc oxidation on Mg-11Gd-1Y-0.5Zn (wt.%) magnesium alloys was investigated by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The relation of phase ...The regulation of ceramic coating formed by micro-arc oxidation on Mg-11Gd-1Y-0.5Zn (wt.%) magnesium alloys was investigated by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The relation of phase structure and corrosion resistance of MgO coating formed by micro-arc oxidation in different growth stages was analyzed. The results showed that the growth of coating accorded with linear regularity in the initial stage of micro-arc oxidation, which was the stage of anodic oxidation controlled ...展开更多
The intergranular corrosion and exfoliation corrosion of 2195 Al-Li alloy treated by multi-step heating-rate controlled aging （MSRC） are studied. The corrosion features of 2195 Al-Li alloys which are respectively tr...The intergranular corrosion and exfoliation corrosion of 2195 Al-Li alloy treated by multi-step heating-rate controlled aging （MSRC） are studied. The corrosion features of 2195 Al-Li alloys which are respectively treated by high-temperature nucleation MSRC （H-M） and low-temperature nucleation MSRC （L-M） are contrasted. And the corrosion mechanism of 2195 A1-Li alloy is also discussed from the viewpoint of microstructure （types, distribution, etc.） of the strengthening phase. The results show that 2195 A1-Li alloy after H-M is more susceptible to intergranular corrosion and exfoliation corrosion than that of alloy after L-M. The degree of intergranular corrosion increases with the increase of predeformation amount and the surface parallel to the rolling direction is more prone to exfoliation corrosion. The main reason of intergranular corrosion and exfoliation corrosion is the formation of corrosion galvanic couples among T1 phase, θ＇ phase and grain boundary precipitate-free zones （PFZ）.展开更多
基金Project(MKPT-02-181) supported by the National Defense Science and Technology Industry Committee of China
文摘The effects of Hg and Ga on the electrochemical corrosion behavior of Mg-5%Hg (molar fraction) alloys were investigated by the measurement of polarization curves and galvanostatic test. The microstructure of the alloys and the corroded surface of the specimens were investigated by scanning electron microscopy, X-ray diffractometry and emission spectrum analysis. It can be concluded that the addition of 1%Ga (molar fraction) reduces corrosion current density from 26.98 mA/cm2 to 2.34 mA/cm2; while the addition of 1%Hg (molar fraction) increases corrosion current density. The addition of Ga and Hg both promotes the electrochemical activity of the alloys and the influence of Ga is more effective than Hg. Mg-5%Hg-1%Ga alloy has the best electrochemical activity, showing mean potential of -1.992 V. The activation mechanism of the magnesium alloy produced by Hg and Ga was put forward. Magnesium atoms are dissolved in liquid Hg and Ga to form amalgam and undergo severe oxidation at the amalgam/electrolyte interface.
基金Project supported by the Natioanl Defence Major Safety Foundation of China (6133002B2008)
文摘The regulation of ceramic coating formed by micro-arc oxidation on Mg-11Gd-1Y-0.5Zn (wt.%) magnesium alloys was investigated by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The relation of phase structure and corrosion resistance of MgO coating formed by micro-arc oxidation in different growth stages was analyzed. The results showed that the growth of coating accorded with linear regularity in the initial stage of micro-arc oxidation, which was the stage of anodic oxidation controlled ...
基金National Basic Research Program of China(2010CB934700)
文摘The intergranular corrosion and exfoliation corrosion of 2195 Al-Li alloy treated by multi-step heating-rate controlled aging （MSRC） are studied. The corrosion features of 2195 Al-Li alloys which are respectively treated by high-temperature nucleation MSRC （H-M） and low-temperature nucleation MSRC （L-M） are contrasted. And the corrosion mechanism of 2195 A1-Li alloy is also discussed from the viewpoint of microstructure （types, distribution, etc.） of the strengthening phase. The results show that 2195 A1-Li alloy after H-M is more susceptible to intergranular corrosion and exfoliation corrosion than that of alloy after L-M. The degree of intergranular corrosion increases with the increase of predeformation amount and the surface parallel to the rolling direction is more prone to exfoliation corrosion. The main reason of intergranular corrosion and exfoliation corrosion is the formation of corrosion galvanic couples among T1 phase, θ＇ phase and grain boundary precipitate-free zones （PFZ）.
