Microstructural characterization of Al/Fe functional graded materials

This study uses functionally graded material (FGM) consisting of aluminum (Al) and iron (Fe) produced by powder metallurgy method with different microstructures. Al and Fe powders are prepared, mixed at different ratios for each step, and compressed by the hot pressing method to obtain FGM. The four layer FGM composite was fabricated by employing powder metallurgy method. The layers were stacked with a surface of Al and Fe 80–20 wt% on top (1st layer) with succeeding layers of Al and Fe at (60–40 wt% (2nd layer), 40–60 wt% (3rd layer), and 20–80 wt% (4th layer)). The distributions at interfaces between the stages are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Obtained data indicate that Al and Fe are homogeneously distributed in the structure in all grades. Increasing the Fe ratio in the layers creates porosity in the Al phase. A Scherrer–Warren equation calculates grain sizes and the lattice parameters in XRD analyses. Vickers indentation is used to determine the hardness of the stages and interstages of the FGM. It is shown that the microstructural and mechanical properties of FGM composites increase by increasing Fe material composition. The results of 4th grade (20% Al + 80% Fe) composite showed improved interface layer microstructure and a maximum hardness of 105.75 HV for grades and 97 HV for interfaces of the FGM composite.