Study On Microstructure And Properties Of Mg-Gd-Y-Zn-Mn-Ni Alloy

Magnesium alloys are widely used in various fields due to their high specific strength and high specific rigidity.The addition of rare earth elements has further improved the comprehensive performance of magnesium alloys,so the research on rare earth magnesium alloys has become a hot spot in recent years.In this paper,Mg-10Gd-3.5Y-0.7Zn-0.9Mn-0.6Ni alloy was prepared by traditional smelting and casting.The effects of solid solution treatment,rolling and aging treatment on the microstructure and properties of alloys were investigated.The purpose is to provide a theoretical basis for the production and application of the alloy.The findings are as follows:The microstructure of the as-cast alloy is uneven.The coarse and continuous networked eutectic phases are distributed at the grain boundaries.Its hardness,tensile strength,elongation and corrosion rate are 85.79 HV,235.79 MPa,5.1% and 0.0078g/cm2/h,respectively.After the solid solution treatment,a large number of networked eutectic phases are dissolved,and the LPSO phase is precipitated.The hardness,tensile strength,elongation and corrosion rate of alloy is 101.96 HV,261.73 MPa,4.5% and 0.0055g/cm2/h after solid solution at 540? for 4 hours.After the rolling deformation,the grains of alloys were gradually refined,and there were mainly intermittent networked eutectic phases and strip-shaped phases in the structure.As the amount of rolling deformation increases,the number of twins gradually increased,and the intersection of the twins played a role in refining the grains.The increase in the amount of deformation could increase the dislocation density inside the grain,increase the lattice distortion,and generate a large number of high potential energy regions,making it easier for new grains to nucleate in the high potential energy region,which could achieve sufficient dynamic recrystallization by increasing the number of nucleation.The alloy with 30% deformation had sufficient recrystallization and fine grain size.Its hardness,tensile strength,elongation and corrosion rate were 105.79 HV,332.59 MPa,3.1% and 0.0058 g /cm2/h,respectively.With the increase of annealing temperature(200?-300?),the twins gradually disappeared,and the speed of static recrystallization accelerated.After annealing at 300?for 1 hour,the grains of the alloy basically became fine equiaxed grains,and their hardness,tensile strength,elongation and corrosion rate reached 110.79 HV,321.54 MPa,7.8% and 0.0037g/cm2/h,respectively.When the annealing temperature was increased to400?,some grains grew abnormally,the alloy structure was extremely uneven,and the strength,plasticity and corrosion resistance were reduced.