Proton irradiation creep of beta-silicon carbide

In situ irradiation creep behavior of chemically vapor-deposited (CVD) polycrystalline beta silicon carbide (β-SiC) has been studied using proton beam of energies 2.8 MeV and 3.2 MeV. Experiments were conducted at 1183 K and at stresses of 18.5 MPa and 97.9 MPa between dose rates of 1.5 and 2.45 × 10−6 dpa/s. Strain was measured using a laser speckle extensometer (LSE) and a linear variable differential transformer (LVDT), and temperature was measured using a 2-dimensional infrared pyrometer. Results showed that the total strain rate increased with increasing stress and dose rate. Shifts of XRD peaks following proton irradiation of SiC at 1183 K indicated that swelling had occurred and that it increased with dose. A uniform expansion of the lattice with no X-ray line broadening clearly indicated that the swelling at doses up to 0.37 dpa was due to single point defects. The swelling rate was determined and subtracted from the measured total strain rate to obtain the true creep rate. The creep rate was found to exhibit a linear dependence on the applied tensile stress, and on dose rate to the third power.