|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Magnesium Technology 2017
||Excimer Laser Processing of Al Containing Mg Alloys for Improved Corrosion Resistance
||Michael Anthony Melia, John R Scully, James M Fitz-Gerald
|On-Site Speaker (Planned)
||Michael Anthony Melia
The implementation of Mg-based alloy components in Cl- containing environments is limited by the poor intrinsic corrosion resistance of the starting alloys. Galvanic coupling of secondary phase particles to the Mg matrix combined with Mg’s low electrochemical potential result in accelerated cathodic kinetics, the controlling reaction of Mg corrosion. To mitigate this behavior, localized dissolution of secondary phases by laser processing was performed on three Al containing Mg alloys; AZ31B-H24, AM60B, and AZ91D. Complete and mixed dissolution of secondary phases was observed by electron and chemical microscopy. An order of magnitude increase in the electrochemical impedance estimated corrosion resistance and order of magnitude reduction in cathodic kinetics was observed for the laser processed specimens immersed in a 0.6M NaCl solution (18 to 60 hours). The dramatic increase in corrosion resistance stems from the reduced density of electrochemically noble secondary phase particles and localized enrichment of Al.