Direct fabrication of engineering ceramic components by additive manufacturing (AM) is a
relatively new method for producing complex mechanical structures. This study investigates how
a second-phase doping may affect Al2O3 ceramic parts deposited by AM with a laser engineered
net shaping (LENS) system. In this study, ZrO2 and Y2O3 powders are respectively doped into
Al2O3 powders at the eutectic ratio as second-phases to improve the quality of a deposited part.
The deposited Al2O3, Al2O3/ZrO2 and Al2O3/YAG (yttrium aluminum garnet) parts are examined
for their micro-structures and micro-hardness, as well as defects. The results show that doping of
ZrO2 or Y2O3 as a second-phase performs a significant role in suppressing cracks and in refining
grains of the laser deposited parts. The micro-hardness investigation reveals that the
second-phase doping does not result in much hardness reduction in Al2O3 and the two eutectic
ceramics are both harder than 1500 Hv. The study concludes that the second-phase doping is
good for improving laser deposited ceramic parts.Mechanical Engineerin
