Effects of T6 Treatment on Corrosion Properties of ZK61M Magnesium Alloy
The extruded ZK61M magnesium alloy was solid soluted at 450℃for 24 h,and then subjected to 180℃aging treatment for 4～10 h.The corrosion properties of magnesium alloys in extrusion,solution and aging state at dif-ferent time were investigated by hydrogen evolution method,weight loss method and electrochemical test method.The microstructure,corrosion products and corrosion morphology of the alloy were observed by optical microscope and scanning electron microscope,and phase constituent was analyzed by energy spectrum and XRD.The results indicate that the solution and aging treatment can change the size and distribution of the second phase in the structure of ZK61M magnesium alloy,and then improve the corrosion resistance of the alloy.With the alloy aged for 4 h,the continuous distribution of granular second phase is precipitated at the grain boundary of the alloy,which reduces the corrosion rate and presents the desirable corrosion resistance.With the increase of aging time,the number of the second phase in the alloy is increased,and the uneven distribution of massive and strip precipitates appear,which reduce the corrosion resis-tance of the alloy.
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