Effect Of Zn Content On Microstructure And Properties Of Mg-Y-Sm-Zr Alloy

Magnesium alloys are attracting the attention of many researchers because of their low density,high specific strength and specific stiffness,and excellent anti-vibration,electromagnetic shielding and recyclability.At the same time,magnesium alloys are also used as the lightest structural materials.Widely used in aerospace,automotive,electronic communications and other industries.However,magnesium alloy materials also have some innate defects,and their corrosion resistance and high temperature mechanical properties are poor,which limits their further application.Studies have shown that trace amounts of rare earth elements can effectively improve the microstructure and properties of magnesium alloys.Therefore,the research of rare earth magnesium alloy has important practical significance.In this paper,Based on the Mg-4Y-4Sm-0.5Zr magnesium alloy,Mg-4Y-4Sm-xZn-0.5Zr?x=0,0.3,0.6,1wt%?alloy was obtained by adding different contents of Zn.This experiment adopts the conventional metal mould to prepare rare earth magnesium alloy,subsequent use solid solution aging treatment.The effects of different Zn contents on the microstructure and mechanical properties of Mg-4Y-4Sm-0.5Zr alloy were analyzed by means of optical microscopy,X-ray diffractometry,scanning electron microscopy and energy spectrum analysis,microhardness and tensile properties.The following research results were obtained:?1?The main component of the precipitated phase of Mg-4Y-4Sm-0.5Zr alloy is Mg₅?SmY?.After adding Zn element,the grain size of the alloy does not change significantly,the number of precipitated phase increases,and a new compound Mg₁₂?YZn?is formed.The strength and hardness of the alloy are optimized when the Zn content reaches 0.6 wt%,and the elongation of the alloy increases with the increase of the Zn content.?2?After the solution treatment of Mg-4Y-4Sm-xZn-0.5Zr alloy,the eutectic phase in Mg-4Y-4Sm-0.5Zr alloy and Mg-4Y-4Sm-0.3Zn-0.5Zr alloy is basically dissolved in the alloy.In the matrix,the grain size of the alloy is increased compared to the as-cast state,while some residuals remain in the Mg-4Y-4Sm-0.6Zn-0.5Zr alloy and the Mg-4Y-4Sm-1Zn-0.5Zr alloy.The eutectic phase was not dissolved in the matrix,and the grain size of the alloy did not change significantly compared to the as-cast state.?3?Mg-4Y-4Sm-0.5Zr alloy forms a new compound Mg12?YZn?after adding Zn element.Excessive Mg12?YZn?phase consumes rare earth elements in magnesium alloy,reduces the number of precipitated phases,and makes magnesium alloy The strengthening effect is weakened,but the plastic deformation ability of the magnesium alloy can be improved,and the elongation of the magnesium alloy can be improved.?4?After T6 treatment,the strength of the alloy increases first and then decreases with the increase of Zn content,while the elongation of the alloy increases continuously.The optimum composition of the alloy is Mg-4Y-4Sm-0.6Zn-0.5Zr,and the best mechanical properties are The tensile strength is 366 MPa,the yield strength is 282 MPa,and the elongation is 6.2%.