Study On Microstructure And Properties Of Mechanical Alloying Mg-Zn-Y/Mg-Zn-Al-Mn Alloy

As a lightweight structural material,magnesium alloy has broad application prospects and development space in the fields of electronic science and technology,automobile manufacturing,aerospace,biological science and medical treatment.However,due to the high chemical activity and poor corrosion resistance of magnesium alloy,its application range is limited.Therefore,studying the corrosion of magnesium alloy and improving its corrosion resistance have important practical significance to expand its application range.In this paper,high purity Mg,Zn,Al,Y,Gd,Mn alloy powders were used as raw materials to prepare Mg-4/8Zn-10Y alloy with milling time of 5h,20h,40h,60h,120h,200h,Mg-1Zn-9Al-0.3Mn alloy with milling time of 5h,20h,40h,Mg-1Zn-9Al-x Y-0.3Mn(x=1%,3%,5%)alloy,Mg-1Zn-9Al-y Gd-0.3Mn(y=3%,5%,7%)alloy with milling time of 20h,40h by high energy ball milling and hot pressing sintering process.The phase composition and microstruc-ture of the alloy were studied by XRD,OM and SEM.The microhardness and corrosion resistance were tested and the corrosion mechanism was analyzed.Mg-4/8Zn-10Y alloys with different milling time are composed of?-Mg phase,Mg₁₂YZn and Mg₂₄Y₅.The microstructure is distributed in groups or groups.With the increase of milling time,the grain size of the alloy is refined,and the microstructure is evenly distributed.The second phase is gradually distributed in a continuous network.The potentiodynamic polarization curves of Mg-4/8Zn-10Y alloy with different milling time in 3.5%Na Cl aqueous solution were passivated to varying degrees.With the increase of milling time,the self-corrosion potential of the alloy moves forward and the corrosion current density decreases.After ball milling for more than 40h,the self-corrosion potential and corrosion current density did not change significantly.The corrosion kinetics curves of Mg-4/8Zn-10Y alloy immersed in 3.5%Na Cl aqueous solution with different milling time showed a linear upward trend.With the increase of milling time,the average corrosion rate of the alloy decreased.When the milling time exceeded 40h,the average corrosion rate was close,which was related to the network distribution of the compound phase.The corrosion resistance of Mg-4/8Zn-10Y alloy after milling for 40h was relatively good.Mg-1Zn-9Al-0.3Mn alloys with different milling time are composed of?-Mg phase and Mg₁₇Al₁₂ phase.In the Mg-1Zn-9Al-0.3Mn alloy,Y and Gd were added respectively to produce new compound phases Al₂Y and Al₂Gd.The microstructure of Mg-1Zn-9Al-0.3Mn series alloy is group or granular distribution.With the increase of milling time,the microstructure of the alloy is refined and evenly distributed.The passivation degree of potentiodynamic polarization curves of Mg-1Zn-9Al-0.3Mn series alloys with different milling time in 3.5%Na Cl aqueous solution was not obvious.With the increase of milling time,the self-corrosion potential of the alloys shifted positively,the corrosion current density decreased,and the corrosion resistance of the alloys increased.The corrosion kinetics curves of Mg-1Zn-9Al-0.3Mn series alloys with different milling time in 3.5%Na Cl aqueous solution showed a linear upward trend.With the increase of milling time,the slope of the corrosion kinetics curve of the alloy decreased,and the corrosion resistance of the alloy increased.In the Mg-1Zn-9Al-Y/Gd-0.3Mn alloy with the same milling time,the Y content increased from 1%to 3%and the Gd content increased from3%to 5%.The corrosion current density decreased,the average corrosion rate of the alloy decreased,and the corrosion resistance was improved.Y content increased to 5%and Gd content increased to 7%,the second phase content increased,promoted the corrosion of the alloy,the average corrosion rate increased,and the corrosion resistance decreased.