The Influence Of Super Gravity Field On The Solidified Structure And Properties Of Al-Zn-Mg-Cu-Zr(Sc) Alloy

Super gravity solidification technology was used in this paper.Al-Zn-Mg-Cu-Zr-Sc alloys without different Zr and Sc content was made by being solidified under different gravity fields,and the influence of super gravity field on the microstructures and hardness was discussed and investigated.After 0.05%,0.10%,0.15% Zr were added to the alloys respectively,the size of grains on the top and in the center of alloys were barely refined comparing with the alloy without Zr.However,the grains at the bottom of alloys were refined effectively.After 0.05%,0.10% Zr were added to the alloys respectively,the average size of grains at the bottom of alloys decreased from 47 ?m to23 ?m,37 ?m.After 0.15% Zr was added to the alloy,the grains at the bottom became very coarse,some grains' size even exceeded 100 ?m.The results also showed that Zr can foster the formation of non-equilibrium entectic phase on grain boundaries.After0.15% Zr was added to the alloy,non-equilibrium entectic phase on grain boundaries became lamellar.The right amount of Zr can promote the hardness of the alloys solidified under super gravity field.After 0.05% Zr were added to the alloys respectively,the hardness of the alloy were promoted from HV 118.1 of the alloy without addition of Zr to HV 134.7.The influence of Sc addition on the microstructures and hardness of Al-Zn-Mg-Cu-Zr-Sc alloys solidified under 5000 g super gravity field was studied.It turned out Sc addition can not refine the grains of Al-Zn-Mg-Cu-Zr-Sc alloys.But appropriate amount of Sc can produce uniforming equiaxed grains in the alloys.It was most effective when 0.3 % Sc was added to the alloys.The hardness values of the alloys decreased after Sc was added.The influence of super gravity field on the microstructures of Al-Zn-Mg-Cu-Zr-Sc alloys was investigated.It turned out that super gavity field can refine the microstructures of Al-Zn-Mg-Cu-Zr-Sc alloys.With super gravity increasing,the refining effect increased at first,however,then became stable.While the super gravityincreasing from 1g to 4000 g,the average grain size was refined from 92?m to 26?m.The refining effects of different parts of the alloys were not the same.Grains in the center of the alloy samples got the most effective refinement,grains in the bottom of the samples took second place,grains at the top of the samples was the last.Super gravity field can promote the hardness of Al-Zn-Mg-Cu-Zr-Sc alloys.With super gravity field increased from 1 g to 5000 g,the hardness of the alloys were promoted from HV 75.3 to HV 125 by 66%.