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This work concerns the microstructure-mechanical properties relationship in Al 2 O 3 /SmAlO 3 composites prepared by hot pressing at temperatures from 1450 °C to 1650 °C. Dense samples have been prepared using co-precipitated trigonal α -Al 2 O 3 and orthorhombic SmAlO 3 at the pseudo-binary eutectic composition. The overall microstructure coarsens with increasing processing temperature, but the nanoscale precipitates within α -Al 2 O 3 and SmAlO 3 grains contribute to coherency strains and distortions in Al 2 O 3 /SmAlO 3 prepared at 1650 °C. The intragranular SmAlO 3 precipitates in Al 2 O 3 grains exhibit semi-coherent interface and an orientation relationship of the intragranular phase SmAlO 3 and alumina matrix close to two different zone axes, namely [ 2 3 ¯ 1 ] SmAlO 3 and [ 4 ¯ 401 ] Al 2 O 3 . Consequently, significant strengthening effect is found from the measured hardness values on the sample sintered at 1650 °C. The measured flexural strength and single edged notched beam fracture toughness of the Al 2 O 3 /SmAlO 3 ceramic are comparable to traditional secondary phases reinforced alumina composites. The sample sintered at 1500 °C exhibits a flexural strength of 558 MPa and a fracture toughness of 5.59 MPa⋅m1/2. [ABSTRACT FROM AUTHOR]