SiC nanoparticle-reinforced Al2O3 matrix composites : Role of intra- and intergranular particles

• Published in: Journal of the European Ceramic Society Vol. 17; no. 7; pp. 921 - 928
• Main Authors: XU, Y, ZANGVIL, A, KERBER, A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 1997
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; Miscellaneous; Technical ceramics; Grinding (comminution); Rupture; Mechanical properties; Dispersion reinforced material; Oxide ceramics; Submicron particle; Fracture toughness; Hot pressing; Composite materials; Silicon Carbides; Manufacture; Microstructure; Alumina; Nanocrystal
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/s0955-2219(96)00164-1

Submicron (or "nanocrystalline") SiC-reinforced Al2O3 matrix composites were prepared by co-milling followed by hot-pressing at 1650 C. Both intra- and intergranular SiC particles were present. The volume ratio for intra- to intergranular particles was approximately 30:70 to 6 vol% SiC composites and 20:80 for 12 vol% SiC composites. The intragranular SiC (50-200 nm) formed mainly by growth of the Al2O3 matrix grains, while Zener pinning, mainly by the larger (200-300 nm) particles, was thought to effectively limit the Al2O3 grain size. Approximately 15% toughening was achieved by incorporating 12 vol% SiC nanoparticles into the matrix. The intergranular particles provided most of the toughening, mainly through a SiC particle-attracted crack deflection mechanism and crack impediment. No evidence was found of toughening by the intragranular particles, although they did cause some grain refinement by dislocation sub-boundary formation. A mixed fracture mode was observed, changing to a mostly intergranular mode with increasing volume of SiC particles. 19 refs.