Study on Microstructures and Mechanical Properties of As-cast Mg-12Gd-xZn-0.5Zr Alloy
The microstructures and mechanical properties of the Mg-12Gd-xZn-0.5Zr(x=0,0.5％,1.0％,1.5％,mass fraction)alloy were studied by X-ray diffractometry,OM,SEM,TEM,brinell hardness tester,and tensile test machine.The results show that the as-cast Mg-12Gd-0.5Zr alloy is mainly composed of α-Mg and Mg5Gd uniformly distributed along the grain boundary.Mg5(Gd,Zn)phase is formed when Zn content is increased to 0.5％and Zn/Gd atom ratio is 1∶10.When Zn content is increased to 1.0％and the atom ratio of Zn/Gd is 1∶5,a small amount of lamellar 18R-LPSO(Mg10GdZn)phase is randomly distributed in the matrix.When the Zn/Gd atom ratio is 1∶3,large lamellar 18R-LPSO phases are contin-uously distributed at grain boundaries.When Zn content is 1％,the comprehensive mechanical properties of the alloy are the best.The tensile strength,yield strength,Brinell hardness and elongation of Mg-12Gd-1Zn-0.5Zr alloy are 200.70 Mpa,106.42 Mpa,73.3 HBW and 10.51％,respectively.
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