Interaction effect of second particles on the stress concentration in ZK60 magnesium alloy

Abstract

Second particles play a crucial role in influencing the performance of magnesium alloys. A previous work showed that during the fracture initiation process a competitive relationship exists between micron MgZn2 particles and submicron Mg4Zn7 particles of ZK60 magnesium alloy. Especially, some of the MgZn2 particles were found to be gathered in pairs, which resulted in the interaction effect. In this work, three‐dimensional MgZn2 particles were characterized in terms of size, morphology, and distribution using computed tomography technology. Based on the visualization and quantification results of MgZn2 particles, the typical structural models were established. The relationship between stress concentration and shape ratio induced by a single particle was investigated using finite element computations. Furthermore, empirical equations were proposed to quantify the interaction effect induced by two adjacent particles. The validity of the equations was verified by models based on real particle. Comparing the stress concentration between micron MgZn2 particles and submicron Mg4Zn7 particles, the fracture initiation was confirmed to be caused by Mg4Zn7 particles considering the interaction effect of micron particles. The obtained quantitative information would be useful for understanding the crack initiation of engineering materials.