| In this thesis, the effects of different rare earth Nd on the microstructure andmechanical properties of cast and rolling AZ31magnesium alloy were studied by usingoptical metallographic microscope, thermal simulator, environmental scanning electronmicroscope and X-ray energy spectrometer, tensile properties and hardness test.Properties of different Nd content of magnesium alloy were compared, and influence ofdifferent Nd content on the mechanical properties and deformation behavior ofmagnesium alloy were analyzed, and effect of Nd on the different states of alloysorganizations were studied.The results showed that: the addition of Nd could reduce Mgl7Al12phase and evenmake it disappear. With the increase of Nd, there was more and more fine second phaseAl3Nd formed and refined grain of AZ31magnesium alloy.When the content of Nd was0.4%, the grain was65μm which was the finest, while the average grain size was91μm without Nd, reducing29%. Addition of Nd improved the temperature tensileproperties, and tensile strength of the cast AZ31-x%Nd alloy was175Mpa increased by52%compared with matrix alloy. Addition of Nd improved the hardness of alloy, andhardness of the cast AZ31-x%Nd alloy was65.2HV5at adding0.6%Nd.The addition of Nd refined the microstructure of the rolled AZ31Magnesium alloyeeffectively, and0.4%Nd addition could get the finest grain and it was3μm. Additionof Nd improved the temperature tensile properties, and tensile strength of the rollingAZ31-x%Nd alloy was294Mpa increased by33%compared with matrix alloy andelongation was15.6%at adding0.4%Nd. Addition of Nd improved the hardness ofalloy, and hardness of the rolling AZ31-x%Nd alloy was55.9HV5at adding0.6%Nd.Adding Nd to AZ31alloy improved high temperature oxidation resistance. With theincrease of Nd, the oxidation resistance was better and better. The corrosion rate ofAZ31-x%Nd in5%NaCl salt spray environment decreased with the increase of thecontent of Nd. The corrosion rate of AZ31-0.6%Nd magnesium alloy was the least. |
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