Influence of electron irradiation on self-healing and thermal oxidation of SiC dispersed yttrium silicate composites

Electron irradiation-induced acceleration of self-healing and high-temperature oxidation has been discovered in SiC/Y2Si2O7-Y2SiO5 composites. Bulk samples were produced by pulsed electric current sintering. These samples were exposed to an electron beam from the pulsed intense relativistic electron beam accelerator with a beam energy of 2 MeV at irradiation doses of 10-40 kGy. The self-healing and high-temperature oxidation experiments were carried out at 1100-1300 degrees C for 1-24 h in laboratory air. Electron irradiation significantly improved the self-healing effectiveness. The closure of surface cracks was caused by the volume expansion of SiC via transformation to SiO2 and the outward diffusion of Y3+ ions. Electron irradiation also increased the thickness of the internally oxidized zone, formed by the inward diffusion of O2- ions. Enhanced self-healing and oxidation behavior were associated with defect formation induced by electron beam exposure, which facilitated the diffusion of ions within the crystal lattice.