Toughening behavior of Mg-PSZ with varying amounts of MgO was studied.
$ZrO_2$ and MgO powders were mixed and sintered with solid solution reaction at 1850℃ for 4hrs. The sintered specimens were aged isothermally at 1410℃ for various times. Mechanical properties were measured by 3-point bending and indentation toughness test. X-ray diffraction and SEM micrograph were used for microstructural analysis.
Strength and fracture toughness were increased with proper aging time at MgO contents of 9.66 and 10.17 m/o. Peak-aging was occured at about 2hr in 9.66 m/o and at about 6hr in 10.17 m/o MgO specimens. The 8.18 m/o MgO specimens showed already-over-aged behavior in assintered condition and the 12.49 m/o MgO specimens showed no effective toughening behavior.
X-ray analysis showed the importance of stress-induced phase transformation in toughening. The lenticular morphology of precipitates and its growth with preferred orientations were revealed with SEM.
