In situ observation of crack initiation and propagation of the charged magnesium alloy under cyclic wet–dry conditions

The process of crack initiation and propagation of the charged MgAl9Zn1 alloy in an atmosphere of water vapor under cyclic wet–dry conditions was in situ observed using environmental scanning electron microscope (ESEM). The results showed that crack initiated at scratches after 6 wet–dry cycles, indicating that residual stress caused by scratches promoted crack initiation. With the increase of wetting time, the fracture interval of the cracking β phase enhanced and the crack length increased, implying that hydrogen produced by corrosion reaction participated in the cracking process.