Quantitative assessment of second phase particles characteristics and its role I on the deformation response of a Mg-8Al-0.5Zn alloy

The deformation and fracture characteristics of magnesium alloys are strongly influenced by the second phase particles. This study comprehensively investigates the three-dimensional microstructure of second phase particles, mechanical properties of individual particles and their effect on the bulk deformation behavior of the AZ80 magnesium alloy. X-ray microtomography has been used to quantify the 3D microstructure of second phase particles (Mg17Al12 and Al8Mn5) in terms of volume, morphology, and size. Further, to elucidate the contribution of second phase particles on the bulk deformation of the alloy, mechanical properties of the individual particle were obtained using nanoindentation. Both second phase particles were found to exhibit higher elastic modulus and hardness than the matrix. Post-indentation analysis using a combination of scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed the presence of pile-up in the vicinity of indents made on both the particles. Further, 3D microstructure-based finite element simulations predicted that the damage starts with the fracture of the particles at the sites of high stress concentration which is corroborated with fractography analysis.