Effect of Fe2O3 content on microstructure of Al powder consolidated parts via selective laser melting using various laser powers and speeds

In situ constituents were formed inside an aluminium matrix via selective laser melting (SLM) of Al powder mixed with 5, 10, and 15 wt% Fe2O3 powder (using various laser powers and speeds), in order to investigate the effect of Fe2O3 content on the microstructural characteristics of novel aluminium matrix composites. The unique microstructures such as coralline-like Al-Fe intermetallics were formed by the in situ reaction, being Fe3Al at first but Al13Fe4 soon after that. These coralline-like intermetallics were fragmented (under appropriate laser parameters and/or higher Fe2O3 contents) and mixed up with Al oxide particles, reinforcing the matrix. The higher Fe2O3 increased the formation of other combinations such as Al2Fe, AlFe, and Fe3Al as well as metastable Al oxides in addition to equilibrium Al13Fe4 (Al3Fe) and stable alpha-Al2O3. A very fine, well-bonded, and homogeneous distribution of hard particles was achieved in high Fe2O3 contents, efficiently increasing the hardness and providing an advanced Al matrix composite.