ZL208 alloy was subjected to solid solution treatment at different temperatures(550-580 ℃)for 8 h and aging at 220 ℃ for 16 h,and the effect of solid solution temperature on its microstructure and properties was studied.The results show that after solid solution and aging treatment,the microstructure of ZL208 alloy partially transforms from dendrites to equiaxed crystals.With the increase of solid solution temperature,the size of the second phase particles at the grain boundary decreases firstly and then increases.The tensile strength,hardness and elongation after fracture of the alloy show a trend of first increasing and then decreasing.This is because the increase in solid solution temperature increases the solubility of Cu and Ni atoms in the α-Al matrix,improving the ability of matrix to resist plastic deformation.At the same time,the second phase at the grain boundary can also restrict grain growth,thereby improving the strength and hardness of the alloy.However,when the solid solution temperature is 580 ℃,overburning occurs,which is detrimental to the properties of the alloy.Therefore,the optimal solid solution and aging process for the ZL208 alloy is 570 ℃ ×8 h+220 ℃ × 16 h.After this process,its tensile strength is 336.87 MPa,yield strength is 210.45 MPa,hardness is 97.48 HV0.1,elongation after fracture is 8.56％,and the fracture mode is brittle fracture.
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