Enhanced ductility in proton-irradiated deformed molybdenum – Gaining insights from experiments and molecular dynamics simulations

This study investigates the effects of 7 MeV proton irradiation on the microstructure and mechanical properties of deformed molybdenum (Mo) through a combination of experimental techniques and molecular dynamics simulations. Microstructural characterization via X-ray Diffraction Line Profile Analysis (XRDLPA) revealed high microstrain and dislocation density in unirradiated samples, which decreased and eventually saturated with irradiation. Residual resistivity measurements indicated the formation of irradiation-induced defects that reduced the electron mean free path. Transmission Electron Microscopy (TEM) confirmed the presence of a deformed microstructure in the unirradiated state and revealed the formation and growth of dislocation loops with increasing irradiation dose. Tensile testing showed enhanced yield stress and plasticity in irradiated samples, with fracture surface analysis indicating a transition towards ductile fracture at higher doses. Molecular dynamics simulations corroborated the experimental findings, showing defect saturation at high doses and the formation of ½〈111〉 dislocations, predominantly of edge character. Enhanced ductility in irradiated pre-deformed samples was attributed to the ability of these dislocations and their segments to sustain efficient slip processes. This comprehensive study provides new insights into the dynamic interplay between irradiation-induced defects and mechanical behaviour in deformed Mo, with implications for its use in radiation environments.