Improvement of Fracture Toughness of Al<sub>2</sub>O<sub>3</sub> Composites by Micro-Dispersion of Flaky Refractory Metals Mo, Ta and Nb

Abstract

New simultaneous toughening and strengthening method for Al2O3 composites has been investigated. The study on flake-forming process of refractory metal powders such as Mo, Ta and Nb was carried out using high purity Al2O3 (AKP-30) and easy-sintering Al2O3 (AES-11) matrices applying the wet ball milling. Three-point flexural strength and fracture toughness by means of SEVNB method of Al2O3/Mo, Al2O3/Ta and Al2O3/Nb composites fabricated by hot pressing were evaluated. The micro-dispersion of flaky particles of Mo, Ta and Nb in Al2O3 matrices contributes remarkably to increase of the flexural strength and fracture toughness. The mechanism of improvement in strength and toughness can be induced from SEM observation of the fracture surface and TEM observation of the microstructure. These properties are closely related to the fracture manner of flaky particles and the distribution of nano particles of refractory metals.