Corrosion experiment of four self-developed free-cutting Zn-Al alloys with varied Bi was conducted in the 3.5%NaCl solution

and the comparative testing was performed both in the humid air and dry air.The corrosion behavior was investigated by means of X-ray diffraction(XRD)

field emission scanning electron microscopy

energy spectrum analysis and electrochemistry testing.The results show that the main corrosion exhibits spot corrosion in the alloy.With increasing in the content of Bi

the average rate of corrosion is increased.The Al-rich phase in Zn-Al alloy is easier to be corroded

and the corrosion process belongs to electrochemical corrosion

in which η phase is acted as the anode and Al as cathode.