The Effect Of High-presssure Torsin Pre-deformation On The Aging Treatment Of Mg-Zn-Y Alloy

Magnesium alloy is the most commonly used lightweight metal structure material for its advantage of high specific strength and specific stiffness,high damping coefficient,good electromagnetic shielding performance and easy cutting.Most RE-containing magnesium alloys show an excellent precipitation hardening response;however,Mg–Y–Zn ternary alloys are not precipitation hardenable.In the as-cast Mg-Zn-Y alloy,the precipitated phase?Mg₃Zn₃Y₂?is coarse and there is a component segregation,which restricts the application of Mg-Zn-Y alloys.It is still worth further study on how to improve the properties of Mg-Zn-Y alloy and the appearance of precipitation.In this paper,the solid Mg-Zn-Y alloy was processed by High Pressure Torsion?HPT?deformation and then aged at different temperature.we focused on the microstructure,precipitates and mechanical of the solid Mg-Zn-Y alloy which processed by using OM,XRD,SEM&EDS,TEM and Microhardness measurement.While the TEM was used to analyze the microstructure,precipitates evolution,dislocation and twin morphology of Mg-Zn-Y alloy after High Pressure Torsion for different deformation,variation of microhardness,precipitate dislocation and twin interactions.The results indicated that after HPT deformation treatment,the grain of the alloy was obviously refined,the second phase was broken and disperse distribution,besides there is a a certain?10 1?orientation in the alloy structure,meanwhile a large number of dislocations and twins are introduced into the alloy when the alloy was deformed for 3revolutions,at the begin of aging the second phase preferentially nucleate at dislocations and twins.With the extension of aging time,precipitates can play a role in hindering slip of dislocations and twin.HPT treatment can also reduce the aging temperature of the alloy,accelerate the ageing precipitation rate.With the increase of deformation,the size of precipitates is finer and more uniform,due to the release of stress which accumulated during the process of HPT and the recovery of softening process exceeds the precipitation hardening process,the hardness of the HPT-processed samples decreased at the beginning of the aging,after that an increase in the hardness occurs for the HPT-processed samples when aged for a period of time and then after the local peak-hardness appeared the hardness fell to a constant value of 110±5HV.