Ratcheting behavior of surface‐modified AZ80 magnesium alloy after pre‐corrosion in simulated body fluids with various pH values

Abstract

AbstractAZ80 magnesium alloy was surface treated by micro‐arc oxidation (MAO) and composite of laser shock penning (LSP) and MAO techniques. Untreated and treated specimens were pre‐corroded in simulated body fluids (SBF) with different pH values (pH 4, 7.4, and 9). The ratcheting behavior of all test specimens was experimentally investigated under stress‐controlled loading. The positive or negative value of the ratcheting strain reflects the mechanism of cyclic deformation. The ratcheting strain with negative values is associated with the cyclic deformation being dominated by twinning–detwinning, while the ratcheting strain with positive values is due to dislocation slip playing a dominant role in the cyclic deformation. A higher absolute value of the ratcheting strain means a lower the ratcheting life. Single MAO coating is not conducive to the fatigue life of magnesium alloy in acidic SBF environment, while LSP/MAO composite coating can improve the fatigue life of magnesium alloy under various loading conditions and different pH environment.