Hydrogenation Reaction And Microstructure Transition Of AZ31 Magnesium Alloy By Mechanical Milling In Hydrogen

Magnesium alloy has the lowest density of all lightweight constructional materials used as the basis for constructional alloys. There are many advantages of magnesium and magnesium alloys, such as high specific strength and rigidity, easy to recyclable and so on. Magnesium based alloys which have very important applied value and great potential for applications now have been used in aerospace and other industrial fields. However, the application of Magnesium alloys has been limited due to there low intensity and low deformability. So enhancing the strength and deformability of Mg alloy is the key to the problem. Grain refinement is the best way to enhancing the strength and deformability of Mg alloy.In this paper, the nanocrystalline magnesium alloy powder was prepared by reactive milling in hydrogen and dehydrogenated operation. The best ball milling parameters were confirmed in this paper and the hydrogen concentration curve as the milling time combined with theoretical calculation was confirmed by measuring the decrease of the hydrogen pressure in mill pot. Research on hydrogenation kinetics process was performed while the influencing factor combined with the hydrogenation mechanism was analyzed. Besides, a new hydrogenated kinetics equation for combining the energy transfer with the reacted fraction had been expressed by effective collusion factor. The effect of application of this equation to the experimental was satisfying well.Both of the phase changes of AZ31 magnesium alloy powder before and after ball milling were characterized by X-ray diffraction (XRD). The grain size of AZ31 magnesium alloy powder was calculated by Scherrer equation according to the XRD results. The morphology and microstructure of the final alloy powders subject to ball milling under hydrogen atmosphere treatment were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively.The same microanalysis of AZ31 magnesium alloy powder by milling in argon was performed by XRD, SEM and TEM and the reason why the effect of grain refinement in reactive milling in hydrogen was great was analyzed. Research on the dehydrogenated behavior, parameter and microstructural were also made in this paper.