Speaker
Description
Materials exposed to radiation can undergo undesirable changes, including radiation-induced swelling and creep, hardening, amorphization, phase segregation, and radiation-enhanced corrosion. At the fundamental level these changes are driven by defects that can aggregate into clusters and dislocations and segregate to interfaces, such as grain boundaries. The nature and dynamics of these defects are often difficult to resolve in experiments, particularly over long times, making predictions of materials performance challenging. I will discuss how we address this issue through development of multiscale models capable of simulating long-term evolution of defects in irradiated ceramics, using silicon carbide as an example. With this approach we identified stable defect clusters in irradiated SiC, as well as their dynamics and contributions to experimentally observed swelling. I will also discuss the role and evolution of interfaces in irradiated materials. While it is known that interfaces can act as sinks for defects, much less is understood about how the interfaces themselves evolve to absorb non-equilibrium flux of defects. In particular, I will share our recent discovery of radiation-induced segregation of elemental species in SiC to grain boundaries, a phenomenon previously only known for metals. Radiation-induced segregation can lead to significant changes in the grain boundary stoichiometry, an effect particularly surprising given that SiC is a line compound. Finally, I will give a brief overview of our computational studies of mechanisms underlying materials degradation due to corrosion and mechanical stresses.
