Effect Of Ultrasonic Treatment On Microstructure And Mechanical Properties Of ZM5 Magnesium Alloy

ZM5 magnesium alloy belongs to Mg-Al-Zn magnesium alloy.Because of its light weight,high specific strength and specific stiffness,and good electromagnetic shielding performance,ZM5 magnesium alloy is widely used in 3C electronic products,automotive,aerospace and other fields.However,since the main phase a-Mg in the ZM5 magnesium alloy belongs to a close-packed hexagonal structure,the sliding system is less at room temperature,resulting in poor strength and plastic toughness of the alloy,which limits the further development of its performance potential to some extent.The reason is mainly related to the coarse a-Mg grains.Therefore,it is of great theoretical significance and engineering application value to deeply explore the fine grain strengthening behavior and solidification structure control technology of ZM5 magnesium alloy.In this paper,the microstructure and properties are improved by applying ultrasonic vibration in the ZM5 magnesium alloy melt.The effects of ultrasonic treatment parameters on the microstructure and mccltanical properties of ZMS magnesium alloy are investigated by single factor experiment and orthogonal test.The phase composition of the alloy,the segregation bcliavior of the alloying elements,and the microstructure and fracture morphology of the alloy under different sonication conditions are studied.The research indicates that:Ultrasonic treatment has no effect on the phase composition of ZMS magnesium alloy.It still consists of α-Mg and β-Mg17Al12 phase,ib which a-Mg grows in dendritic form andβ-Mg17Al12 phase distributes in between.Under the ultrasonic treatment conditions,the mierostructure of the a-Mg phase changed from coarse dendrites without ultrasonic treatment to line cquiaxcd crystals,and the average grain size is reduced from 294.0 μm to 103.1 μm.Theβ-Mg17Al12 please,which is continuously distributed between the crystals,is broken into thin strins or snots,and is dispersed on the matrix.As the ultrasonic power and ultrasonic treatment time increase,the grain size and the second phase of the ZM5 magnesium alloy decrease first and then increase.Moreover,the α-Mg grain refining effect is more pronounced when the temperature is near the liquidus.After ultrasonic treatment,the content of Al in the β-Mg17Al12 phase of ZM5 magnesium alloy decreased,and more Al atoms entered the α-Mg matrix,which produced a certain degree of solid solution strengthening effect.At the same time,ultrasonic treatment promotes the uniformity of Al atom distribution.At the same time,ultrasonic treatment has a certain degassing effect on the alloy melt.With the increase of ultrasonic treatment temperature and ultrasonic power and ultrasonic treatment time,the tensile strength,elongation and hardness of ZM5 magnesium alloy show a trend of increasing first and then decreasing,and the comprehensive performance is better than that of conventionally cast alloy.When the ultrasonic treatment temperature T=610℃,ultrasonic power P=740W,ultrasonic treatment time t=80s,the tensile strength of the alloy reached 183.4 MPa,the elongation reached 4%,and the hardness was 67.2 HBW.Among various factors,The ultrasonic treatment temperature has the most significant effect on the average grain size of α-Mg and the mechanical properties of the alloy,while the ultrasonic power is the main factor affecting the size of β-Mg17Al12 phase.The recommended ultrasonic treatment parameters of ZM5 magnesium alloy are:ultrasonic treatment temperature T=610℃,ultrasonic power P=740W,and ultrasonic treatment timet=80s.