The corrosion behavior of nitrogen ion (N2+)-implanted AZ91D magnesium alloy (UNS M11916) in 5 wt% sodium chloride (NaCl) solution was investigated using weight-loss measurement and electrochemical techniques. Ion implantation improved corrosion resistance at doses > 1 x 1016 ions/cm2 (6.5 x 1016 ions/in.2). At doses of 5 x 1016 ions/cm2 (3.27 x 1017 ions/in.2), the mean corrosion rate and maximum pitting depth reached minimums. Impedance spectra drew a capacitive semicircle at 2 x 1016 or 5 x 1016 ions/cm2 (1.3 x 1017 ions/in.2 or 3.2 x 1017 ions/in.2). Additional inductive loops were observed in the lower frequency of untreated or implanted specimens outside this range. The presence of the inductive loop was discussed in terms of corrosion morphology, particularly in terms of the occurrence of pitting corrosion. Monitoring polarization resistance (Rp) was shown to be useful in evaluating effects of ion implantation.

Subject
Pits, Ions, Corrosion resistant alloys, Corrosion rate, Magnesium alloys, Sodium chloride solution, Nitrogen, Magnesium, Pitting, Corrosion resistance, Aluminum alloys, Alloys, Potentiodynamic polarization
Keywords:
alloy AZ91D, chloride, corrosion resistance, electrochemical impedance, inductance loop, ion implantation, magnesium, nitrogen, pitting, polarization resistance
NACE International
1996
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