Abstract Scope |
Comprehensive molecular dynamics simulations have been performed to study the delamination of seven grain boundaries/cleavage planes (Sigma1{111}, Sigm3{111}, Sigm5{100}, Sigm7{111}, Sigm9{411}, Sigm11{311}, and R{100}/{411}) containing a helium bubble. A variety of strain rates, system dimensions, bubble densities, bubble radii, bubble pressures, and temperatures were explored. We found that in general, grain boundaries absorb less energies with decreasing strain rate but increasing bubble areal density, bubble pressure, bubble radius, and temperature. The propensity of grain boundary delamination is sensitive to grain boundary type: The random grain boundary R{100}/{411} is one of the most brittle boundaries whereas the Sigm1{111} cleavage plane and the Sigm3{111} twin boundary are two of the toughest boundaries. The sorted list of grain boundary fracture vulnerability obtained from dynamic tensile test simulations and decohesion energy calculations does not match, confirming the important role of plastic deformation during fracture. Detailed mechanistic analyses are performed to interpret the simulated results. |