Preparation, microstructure and ion-irradiation damage behavior of Al4SiC4-added SiC ceramics

Single-phase Al4SiC4 powder with a low neutron absorption cross section was synthesized and mixed with SiC powder to fabricate highly densified SiC ceramics by hot pressing. The densification of SiC ceramics was greatly improved by the decomposition of Al4SiC4 and the formation of aluminosilicate liquid phase during the sintering process. The resulting SiC ceramics were composed of fine equiaxed grains with an average grain size of 2.0 mu m and exhibited excellent mechanical properties in terms of a high flexure strength of 593 +/- 55 MPa and a fracture toughness of 6.9 +/- 0.2 MPa m1/2. Furthermore, the ion-irradiation damage in SiC ceramics was investigated by irradiating with 1.2 MeV Si5+ ions at 650 degrees C using a fluence of 1.1 x 1016 ions/cm2, which corresponds to 6.3 displacements per atom (dpa). The evolution of the microstructure was investigated by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The breaking of Si-C bonds and the segregation of C elements on the irradiated surface was revealed by XPS, whereas the formation of Si-Si and C-C homonuclear bonds within the Si-C network of SiC grains was detected by Raman spectroscopy.