Conclusion
Laser additive manufacturing was used to synthesize AlCoCrFeNiCu and
AlTiCrFeCoNi coatings on a steel base plate and the effect of laser
parameters on both compositions were studied. The laser power was varied
between 600-1600 W with the laser scan speed varied from 4-12 mm/s while
the powder feed rate and the gas flow rates were kept constant at 2 rpm
and 3 I/min respectively. The study deduced that:
- Optimizing the laser parameters invariably influenced the performance
of the alloys with potential coatings and structural applications.
- The alloys both showed a dendritic structure with FCC and BCC phases.
- The optimized parameters were between 1200-1600 W at 8-12 mm/s with a
50 % overlap. This shows that the right combination of process
parameters is an important factor to producing homogeneous and
defect-free microstructures.
- The AlCoCrFeNiCu HEA showed fewer peaks on the XRD graph and had few
FCC phases compared to the AlTiCrFeCoNi HEA, this is attributed to the
difference in Cu and Ti contents, respectively.
- After the first stage of experiments the AlTiCrFeCoNi HEA had higher
hardness values than the AlCoCrFeNiCu HEA; however, at the second
stage, the AlCoCrFeNiCu HEA showed high hardness than the AlTiCrFeCoNi
HEA. This is attributed to the changes in process parameters and the
introduction of the pre-heating temperature at the second stage.
- Both alloys showed an increase in hardness values at scan speed of 12
mm/s
- The melt pool width, height and bead depth increases with the linear
energy density