The Effect of Y、Ce、Sr Addition on the Microstructures and Mechanical Properties of Magnesium Alloys

　　The Effect of Y、Ce、Sr Addition on the Microstructures and Mechanical Properties of Magnesium Alloys
　　Magnesium alloys offer good combination of mechanical properties, high specific strength and stiffness, superior damping capacity, high thermal conductivity, high dimensional stability, good electromagnetic shielding characteristics and good machinability. The attractive mechanical properties of magnesium and its alloys increase their use for many technical applications, i.e. automobile, aeronautical and aerospace, housing utensils and electronic industries, etc. However, commercial applications of magnesium alloys are limited because of poor creep resistance and poor tensile properties at elevated temperature above 120℃. AZ91D is the widely used Mg-Al alloys in the Alnico magnets industry apply at present, offering a good combination of mechanical properties at ambient temperature, die castability and corrosion resistance. But the worse creep strength restricted its further used. The researcher studied the alloys, heat treatment, squeezing and fast solidifying on the microstructure and mechanical properties of AZ91D magnesium alloys. This experiment mainly study the alloys element on the microstructure and mechanical properties of magnesium alloys through addition Sr and RE (Y and Ce ).The results show that the microstructure of AZ91D alloys were significant refined with Y, Ce and Sr additions. The refinement degree increased with the addition content of alloy element increasing and had needle-shaped Al11Ce3, Al4Sr phase and block Al2Y phase generated. The optimum refinement degree can http://www.999magnet.com obtained, it decreased about 40.2%, 41.6% and 50% compared to the original size. But the microstructure was not refined with the addition content further additions. The microstructure also can be significant refined when the Y、Ce、Sr were composite additions. The vary tendency same to single element addition. The minimum grain size can obtained which decreased about 48.1%、60% and 55.6% compared with initial microstructure size.The spacing interval reducing ofα-Mg dendrites when adding the Y element to