Table 1.
Summary of microstructural evolution in the dependence of layer thickness, laser power, and scanning speed.
| Thick powder bed | t = 75 μm | t = 50 μm | |
|---|---|---|---|
| Morphology (appearance) | Single Al phase-granular structure | Predominantly coralline-like | Semicoralline-like/particulate |
|
| |||
| Oxygen/oxide content | Least oxygen/oxide | Medium oxygen/oxide | Highest oxygen/oxide |
|
| |||
| Predominant phases | Al | Al, Al-Fe intermetallics such as Al13Fe4 and Fe3Al; some oxides (like Fe2+Al2O4) may also be detected | Al, aluminium oxide (Al2O3) plus iron aluminium oxides (e.g. Fe2+Al2O4 and AlFeO3), Al-Fe intermetallics such as Al13Fe4 |
|
| |||
| Increasing laser power | N/A | Development of corallines (mainly Al-Fe intermetallics) and oxide particles from primary Al/Fe2O3 interface—reduction in oxygen/oxide | N/A |
|
| |||
| Lowering scanning speed | N/A | Coarsening of corallines—reduction in oxygen/oxide | Better dispersion and placement of secondary phases |