Analysis of possible deformation mechanisms in helium-ion irradiated SiC

Possible modes of accommodating deformation during physically constrained swelling of SiC during He-ion irradiation (∼2x1022 He/m2 below 200 deg. C) were studied using finite element modeling. When accommodating deformation occurs only by elastic deformation, calculated internal stresses are much higher than the fracture stress for SiC. On the other hand, stresses below the fracture stress result when allowing irradiation-enhanced creep (IEC) to act as an additional accommodation mechanism. For a steady-state IEC compliance coefficient for SiC equal to 6x10-5 MPa-1 dpa-1, the maximum observed von Mises stress was less than the fracture stress of the material. This value for the creep compliance appears to be significantly larger than the few experimentally available measured values for crystalline SiC in the open literature