What are the elements in the nodulizer? There are mg, re, CA, Si, Al, etc. what other rare elements are there? In magnesium alloys, the beneficial effect of rare earth on non-ferrous metals is obvious. It not only constitutes silicon magnesium alloy system, but also has a significant impact on Mg-Al, mg Zn and other alloy systems. The main functions of spheroidizing agent are described in detail below:
(1)Grain refinement
Appropriate rare earth content can refine the grains of magnesium and magnesium alloys. The first is to refine the particles of the matrix. The mechanism of rare earth elements refining magnesium alloy matrix is not the result of heterocyclic nucleation. The effect of rare earth elements on grain refinement of magnesium and its alloys is due to the increase of undercooling at the crystallization front. The second is to prevent recrystallization and grain growth during heat treatment and annealing.
(2)Purify melt
The affinity between rare earth elements and oxygen is greater than that between magnesium and oxygen. Therefore, rare earth elements can react with oxides such as MgO in the melt to form rare earth oxides and precipitate to remove oxide inclusions. It reacts with hydrogen and water vapor in the melt to form cyanide or rare earth oxide for deoxidation. At the same time, it can increase the fluidity of melt, reduce the shrinkage of castings and improve the compactness of castings.
(3)To improve the strength of room temperature alloy, the solid solubility of most rare earth elements in magnesium is large, and the solid solubility changes obviously with the decrease of temperature. Therefore, in addition to solid solution strengthening, rare earth elements are also effective aging strengthening elements in magnesium alloys.
(4) Improve the corrosion resistance of the alloy
By purifying the melt, the harmful effects of impurities (such as iron) are reduced and the corrosion resistance is improved. Improve the thermal stability of the mechanical properties of the alloy
