Preparation Of Grain-refiners And Their Refinement Mechanism Of Magnesium And Magnesium Alloys

The improvement of ability of the plastic deformation for the magnesium alloys though the extensive use of which has become an irreversible trend is still a key issue. It is shown in the practice that the fine equiaxed grains can improve the ability of the plastic deformation of the magnesium alloys; and this turns out that it is very important to find a practical and effective refiner for the refinement of their grain.In this paper, it takes the pure magnesium and AZ31 magnesium alloy as its subjects for the study. It prepares the Mn-30wt.%Al interalloy that contains (?)-AlMn phase as well as the Al-3Ti-3B, Al-5Ti-1B, Al-5Ti-0.2C, Al-3Ti-1C. Furthermore, it makes an analysis of compositional phase of these alloys with X-ray diffraction (XRD). Also, by using EDS, it studies the corresponding mechanism of refinement of magnesium alloy grain. The results shows that refining effect for the grain is obvious when Al-3Ti-3B, Al-5Ti-1B, Al-5Ti-0.2C or Al-3Ti-lC is added into the pure magnesium; the more the proportion, the finer the grains are. However, the Mn-30wt.% Al interalloy which contains the (?)-AlMn phase has little effect to the refinement of pure magnesium. For the AZ31 magnesium alloy, Al-3Ti-3B and Al-5Ti-1B are significant for the grain refinement; both of the optimal ratios were 0.6%; while the Al-5Ti-1B is not so significant as the Al-3Ti-3B.0.6% of the Al-3Ti-1C is the most significant for the grain refinement of the AZ31magnesium alloy, which is 200μm. XRD and EDS show that there is, in the Al-3Ti-1C interalloy, the nucleation mass point A14C3 phase which is similar to a-Mg crystal lattice. For AZ31 alloy, adding 0.4% Mn-30 wt.%Al interalloy that contains (?)-AlMn phase would obtain the best refinement, that is 430μm. Through detecting, the author preliminarily believes that this is because there is the nucleation mass point (?)-AlMn phase which is similar to a-Mg crystal lattice.