Processing‐Related Fracture Origins: I, Observations in Sintered and Isostatically Hot‐Pressed A12O3/ZrO2 Composites

Strengths of sintered Al2O3/ZrO2 composites are much lower than those of hot-pressed composites due to large flaws associated with the sintering process. Fractography has shown that cracklike internal surfaces are at the fracture origins of the sintered materials. It is hypothesized that the cracklike internal surfaces are developed as a result of differential sintering of agglomerates relative to their surrounding powder compact. Isostatic hot-pressing of the sintered composites quickly eliminated the cracklike internal surface. Flaws responsible for fracture of the isostatically hot-pressed composites were low-density regions that are not as easily eliminated.