Abstract
The role of grain size on the developed microstructure and mechanical properties of neutron irradiated nanocrystalline copper was investigated by comparing the radiation response of material to the conventional micrograined counterpart. Nanocrystalline (nc) and micrograined (MG) copper samples were subjected to a range of neutron exposure levels from 0.0034 to 2 dpa. At all damage levels, the response of MG-copper was governed by radiation hardening manifested by an increase in strength with accompanying ductility loss. Conversely, the response of nc-copper to neutron irradiation exhibited a dependence on the damage level. At low damage levels, grain growth was the primary response, with radiation hardening and embrittlement becoming the dominant responses with increasing damage levels. Annealing experiments revealed that grain growth in nc-copper is composed of both thermally-activated and irradiation-induced components. Tensile tests revealed minimal change in the source hardening component of the yield stress in MG-copper, while the source hardening component was found to decrease with increasing radiation exposure in nc-copper.
Highlights
The continuously increasing energy demand, combined with a noticeable depletion in traditional energy resources all over the world, has revived interest in developing advanced nuclear power systems—both fission and fusion based [1]
The average grain size of nc-copper was determined through several methods, including X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) image analyses
The impact of grain size on the response of MG and nc-copper to fast neutron irradiation was assessed by evaluating the mechanical behavior and microstructural evolution in the material pre and post-irradiation
Summary
The continuously increasing energy demand, combined with a noticeable depletion in traditional energy resources all over the world, has revived interest in developing advanced nuclear power systems—both fission and fusion based [1]. Because grain boundaries act as sinks for irradiation-induced point defects, it was hypothesized that nc materials would possess enhanced radiation resistance compared to conventional micrograined (MG) materials [12,13] This is based on the premise that both the thermal stability and mechanical integrity of the nc materials will be maintained under irradiation [14]. The influence of grain size on the density of defect clusters was investigated by Rose et al [17], who observed a proportional decrease in defect density with decreasing grain size in nc ZrO2 and Pd. researchers have reported enhanced radiation resistance characteristics in various ultra-fine grained steel alloys following neutron and ion irradiations when compared to their MG counterparts [18,19,20,21,22]. The scientific and technological importance of this work originates from the profound role of copper in nuclear applications as well as the obvious scarcity of neutron irradiation data in the literature of nc-copper in particular, and nc materials in general
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