Microstructural nature of strengthening and toughening in Al2O3-SiC(p) nanocomposites

摘要

It is demonstrated that neither of the theories onflaw size, surface flaw healing or residual stress adequately andconsistently explain the strengthening and toughening phenomenain Alumina-SiC nanocomposites. SiC presence reduces the amountof amorphous (glassy) silica rich phase (SRP) in thenanocomposite relative to that found in monolithic Alumina andto a level that the effect of SRP is negligible. The reduction ofSRP and the multipliable effect of microstructural features such asdislocations, crack/particle interactions and cleavage steps,observed in these materials at an extraordinarily small interactionsand cleavage steps, observed in these materials at anextraordinarily small scale (due to the nano-size of the SiCparticles), are suggested to be more consistent in explaining thesephenomena. Owing to the nano-scale at which these featuresoperate, which is far below the practical resolution limit of theScanning Acoustic Microscope (SAM), it is also argued that thelatter may not be a good method for studying these materials.