Microstructure, corrosion behavior and hydrogen evolution of USSP processed AZ31 magnesium alloy with a surface layer containing amorphous Fe-rich composite

Abstract The influence of ultrasonic shot peening (USSP) treatment on the microstructure, corrosion behavior and hydrogen evolution of AZ31 magnesium alloy is investigated. An Fe-rich composite in amorphous state is introduced on the surface layer. Microstructure results indicate that nanoscale grains are formed on the surface layer after USSP treatment. Comparing to the untreated AZ31, the charge transfer resistance of the USSP-treated sample decreases by ~410 times and the hydrogen evolution rate increases by ~64 times. The acceleration of corrosion rate is attributed to the micro-galvanic interaction between the nanocrystalline Mg matrix and amorphous Fe-rich composite.