Radiation damage in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"> <mml:mtext>δ</mml:mtext> </mml:math> -phase Pu-Ga alloys

Irradiation can cause severe property degradation of materials (i.e., radioactive aging), which has drawn general interest in both scientific research and engineering applications. In nuclear areas, this is significantly important due to many nuclear materials being radioactive or exposed to radiation environments. Although the basic process of the self-irradiation of actinides and their derivatives has been studied, there is still much that remains elusive, especially for Pu-Ga alloys, one of the most mysterious nuclear materials. Here, we utilize molecular dynamics simulations to study the influence of the incident angle of the U nucleus on the self-irradiation of δ -phase Pu-Ga alloys, also concerning the effect of Ga concentration in the alloys. The generation of defects shows obvious dependence on the U incident angles, where the maximum and ultimate numbers of defects change up to 59% and 38%, respectively. Besides, the ultimate local atomic structures of the materials are also affected. Different U incident angles lead to different collision kinematics and energy transfer efficiencies, which subsequently cause cascade collisions with different paths and scales. Specifically, the coupling of thermal vibrations and geometric alignment in certain directions leads to high variability in defect production. The self-irradiation of δ -phase Pu-Ga alloys with a series of Ga concentrations (ranging from 2 to 7 at. %) is also studied, and the ultimate defect number is found to be the smallest for the alloys with the middle concentration of 5 at. %. This work shows the importance of considering the irradiation angle and element content for the primary damage formation underlying radioactive aging of nuclear materials, which will be useful for the development of strategies to manage aged nuclear materials. This article reports that the incident of U nucleus and Ga concentration have evident influences on the self-irradiation of δ -phase Pu-Ga alloys. • Incident angle of U nucleus and Ga concentration are demonstrated to have an evident influence on the self-irradiation of δ-phase Pu-Ga alloys. • The numbers and distributions of introduced defects are affected by the incident angle of U nucleus or Ga concentration. • The maximum and ultimate numbers of defects introduced in the irradiation can respectively change up to 59% and 38% among different incident angles. • The ultimate defect number is found to be the smallest for the alloys with the middle concentration of 5 at. %. • Different U incident angles cause cascade collisions with different paths and scales, which eventually lead to different radiation damage.