Improved corrosion resistance of Mg alloy AZ31B induced by selective evaporation of Mg using large pulsed electron beam irradiation

Abstract

Large pulsed electron beam (LPEB) irradiation was employed as a surface treatment of magnesium (Mg) alloy AZ31B to enhance its corrosion and wear resistance. Selective evaporation of Mg induced by LPEB irradiation at an energy density of 5 J/cm2 for 40 cycles has led to the formation of an Al-enriched re-solidified layer with nano-grained structure consisting of Mg3.1Al0.9 metastable phase. The formation of such a re-solidified layer after LPEB irradiation has enabled a decrease in corrosion rate of Mg alloy AZ31B in 3.5% NaCl solution. Different equivalent electrical circuit models were proposed to account for the corrosion behavior of untreated Mg alloy AZ31B and those subjected to LPEB irradiation. A decrease in wear depth when compared to that of the untreated alloy suggests an increase in wear resistance of LPEB-irradiated Mg alloy AZ31B. Adhesive wear is the predominant mechanism of untreated Mg alloy AZ31B while abrasive wear mechanism dominates for LPEB-irradiated Mg alloy AZ31B.