Effect of liquid metal environment on nucleation and propagation of fatigue cracks

Promoter

Seefeldt Marc, (Katholieke Universiteit Leuven (KULeuven)), marc.seefeldt@kuleuven.be

SCK•CEN Mentor

Marmy Pierre, pmarmy@sckcen.be, +32 (0)14 33 31 72

Expert group

Structural Materials

SCK•CEN Co-mentor

Gavrilov Serguei , sgavrilo@sckcen.be , +32 (0)14 33 30 67

Short project description

Nuclear plants of the next generation , so called GEN IV reactors, are today a major contender for the safe delivery of clean and environmental respectful energy. Some of these reactors are planned to use a liquid metal eutectic of lead and bismuth (LBE) as a coolant. The eutectic melts at 125°C and then behaves similar to water , is circulated around the reactor core to extract the heat. The  materials  used for the structure of the reactor have to satisfy strict specifications which ensure them to sustain operational cyclic  loadings during   harsh conditions due to  irradiation and environment. The prospective studies already accomplished have shown  that coolants of this type  can have a  negative influence on the mechanical properties of some of the candidate materials. They are corrosive and can induce a degradation of the fatigue performance and fracture resistance.  It was found that under certain conditions, the number of cycles for the initiation of a crack was reduced and that the propagation rate of the crack was increased. Different physical mechanisms have been proposed in the literature to explain the results but none of them was really able to properly describe the observed effects.  Comparison tests have also shown that the environment is a key factor for the materials's response. In an attempt to identify the physical mechanisms controlling the nucleation and propagation of cracks,  experiments in three different media such as vacuum, air and LBE will be conducted in the selected material. The microstructural modifications at the crack tip in the different environments will be observed using techniques such as SEM, TEM and FIB which should allow the candidate to give  a detailed description of the microstructure at the surface of the crack and close below it. These observations will be   correlated with the mechanical results and used to propose an explanation of the mechanisms going on in the presence of LBE.

The minimum diploma level of the candidate needs to be

Master of sciences , Master of sciences in engineering

The candidate needs to have a background in

Physics

Estimated duration

4 years
Before applying, please consult the guidelines for application for PhD.