3D microstructural characterization and mechanical properties of constituent particles in Al 7075 alloys using X-ray synchrotron tomography and nanoindentation

•Combined 3D microstructural characterization and mechanical properties of inclusions in Al 7075 alloys.•3D microstructural characterization of inclusions was obtained by X-ray synchrotron tomography.•Mechanical properties of inclusions was obtained by CSM technique in nanoindentation.•Quantitative characterization of volume fraction, size, and morphology of inclusions and porosity.

Inclusions (constituent particles) in Al 7075 alloys can be classified as Fe-bearing and Si-bearing inclusions. They play important roles in the deformation behavior, particular under fatigue loading. Thus, in order to understand the deformation behavior under fatigue loading of Al 7075 alloys, it is important to investigate the size and distribution of these inclusions and porosity in the material, along with their mechanical properties. X-ray synchrotron tomography was used to obtain the 3D microstructure of these microconstituents in Al 7075 alloy. Quantitative analysis in terms of volume, size, and morphology of inclusions and porosity was performed. The mechanical properties of these constituent particles along with the matrix were obtained using nanoindentation. Scanning electron microscopy (SEM) and EDS was used to analyze the indentations after testing. The Young’s modulus and hardness of all inclusions were higher than the matrix. The Young’s modulus values of Al7Cu2Fe, Al23Fe4Cu, and Mg2Si were measured to be 160.2 ± 10.9, 139.5 ± 3.7, and 94.8 ± 7.5 GPa respectively. Values of hardness of Al7Cu2Fe, Al23Fe4Cu, and Mg2Si were 8.8 ± 0.9, 7.5 ± 0.8, and 5.2 ± 0.5 GPa respectively. Comparison of these values with nanoindentation data in the literature was also conducted.