▎ 摘　　要

Anisotropy in mechanical properties is commonly reported in ceramics prepared by Spark Plasma Sintering (SPS). Here we investigate SPS preparation of isotropic alumina by adding pyrolytic carbon with and without multilayer graphene as sintering additives. Anisotropy in grain morphology, elastic modulus, microhardness and fracture toughness (KIC) is evaluated by a comparison of measurements along directions parallel and perpendicular to the external electric field in SPS. Results show that anisotropy in the first three parameters is insignificant except KIC. {0001} fiber texture attributes to anisotropy in pure alumina. As pyrolytic carbon adds, equiaxed grains in alumina are significantly refined mainly due to pinning effect and KIC increases because of induced microcracking. Anisotropy in KIC of the composite is reduced due to scattering of the {0001} fiber texture. When multilayer graphene with in-plane size in micron is further introduced, anisotropy in KIC is diminished at the cost of embrittlement.