In situ TEM observation of dislocation movement through the ultrafine obstacles in an Fe alloy

Dislocation movement through ultrafine obstacles in a thermally aged Fe–Cu alloy has been studied by in situ transmission electron microscope observation. A very effective technique for quantitative estimates of radiation embrittlement is proposed. The obstacle strength has been estimated from the critical bow-out angle, φ, of dislocations. The increase in shear stress, which is estimated from the averaged strength of ultrafine obstacles and the averaged distance between the two neighboring obstacles on a dislocation in the in situ observation, is in good agreement with the hardening obtained from macroscopic mechanical tests. This technique is very useful to predict the mechanical properties of irradiated fusion and fission reactor materials from the microstructure obtained from experimental observations and/or the computer simulations.