Microstructure Optimization of Cold Sprayed M2052 Alloy Using Post-Processing Heat Treatment for Tailoring Damping Capacity
Cold spray,as a solid-state additive manufacturing process,has been attracting an increasing interest due to low heat input,which avoids grain growth,phase transformation,and high thermal stress.This feature is beneficial for high damping Mn-Cu alloy through limiting oxidation and formation of hot cracks.However,high dislocation density formed because of extensive plastic deformation,pores,and cracks result in the low damping capacity in the as-deposited Mn-Cu alloy.Thus,new strategy was introduced for improving damping capacity in cold sprayed Mn-20Cu-5Ni-2Fe(M2052)alloy,and microstructure evolution was studied after different heat treatments.Insufficient plastic deformation of powders during cold spraying processing results in the formation of the pores at the boundaries of the powders.After solid solution at 850℃for 1 h an obvious decrease in number of the pores is found,which is related to atomic diffusion at higher temperature.The dynamic recrystallization leads to the formation of a large number of nano-sized grains at the particle bonding interface.After solid solution at 850℃for 1 h and ageing at 420℃for different times recrystallization and grain coarsening take place.Ageing treatment at 420℃for up to 72 h leads to spinodal decomposition of the fcc-austenite.With increasing ageing time martensitic transformation temperature of the cold sprayed M2052 alloy increases,which is attributed to the increase in the Mn content in the rich-Mn matrix due to the increase in the spinodal decomposition degree.The cold sprayed M2052 samples after solid solution at 850℃for 1 h and ageing at 420℃for 24 h show higher damping capacity Ψ0.08%=2πQ-1≈26%(at room temperature).
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