Atomistic insight into the effects of order, disorder and their interface on defect evolution

It is well established that chemically-disordered alloys exhibit good irradiation resistance due to their ability to self-healing. On the other hand, ordered phases are usually utilized as strengthening components in alloys. In this work, the effects of ordering degree and the order/disorder interface on primary damage production, including point defects, defect clusters, and dislocations, are investigated through atomistic simulations. Exemplified by the Ni–Al and Ni–Fe alloy systems, we first compare defect evolution in the ordered and disordered phases. Our results indicate that the degree of order has profound influences on defect evolution, especially defect clustering properties. Specifically, ordered Ni₃Al and disordered NiFe can strongly suppress defect growth, ascribing to their particular melting temperature and defect diffusion properties. For mixture alloys containing order/disorder interfaces, our results suggest that the ordered phase gets disordered gradually under displacement damage. The disordering is facilitated by the disparity of defect diffusivities between the ordered and disordered phases. These results shed light on the atomistic mechanism underlying the irradiation response of ordered and disordered alloys as well as their mixture systems, which advances the understanding of the defect process in superalloys and recent ordered-precipitate-strengthened high-entropy alloys.