EFFECTS OF Sn ON MICROSTRUCTURES AND CORROSION RESISTANCE OF Mg-6Al-1.2Y-0.9Nd MAGNESIUM ALLOY

Effects of Sn addition on corrosion rate of Mg-6Al-1.2Y-0.9Nd magnesium alloy in 3.5%NaCl solution were studied by the static mass-loss tests.The microstructures of the alloys were observed by optical microscope and the morphologies of corrosion surface were analyzed with scanning electron microscopy.The results indicated that with the addtion of 1%Sn,the crystal grain size of the Mg-6Al-1.2Y-0.9Nd magnesium alloy was obviously refined,the microstructure was more homogeneous.But when the addition of Sn is more than 1%,the precipitates increase and they cause the trend of coarsening and segregation.Furthermore,in NaCl solution the corrosion rate of Mg-6Al-1.2Y-0.9Nd magnesium alloy decreases firstly and then increases with the increase of Sn content.With the addtion of 1%Sn,the corrosion rate of the alloy was the lowest,and the corrosion resistance was improved remarkably.