Dynamics of Radiation Damage in AlN Ceramics under High-Dose Irradiation, Typical for the Processes of Swelling and Hydrogenation

Abstract

The use of nitride ceramics, in particular AlN, as structural materials for nuclear power is primarily limited by their resistance to swelling and hydrogenation processes due to the accumulation of poorly soluble helium and hydrogen ions in the structure of the surface layer. In this regard, research in this area is of great importance not only from a fundamental point of view, but also practical, since any new data on radiation resistance can make a great contribution to the development of the theory of resistance to radiation influences of structural materials of a new generation. This work is devoted to a systematic study and comparative analysis of the dynamics of radiation damage during high-dose irradiation with protons and helium ions in nitride ceramics, which have great potential for use as structural materials for GenIV reactors. The choice of irradiation doses of 1 × 1017–5 × 1017 ion/cm2 is due to the possibility of modeling the processes of radiation damage characteristic of displacements of 10–50 dpa. During the study, the dependences of the change in the dielectric and conductive characteristics of nitride ceramics depending on the radiation dose, as well as on the type of ions, were established. The kinetics of degradation and accelerated aging was determined depending on the type of exposure. The mechanical and strength properties of ceramics were determined.

Study of Changes in Optical and Heat-Conducting Properties of AlN Ceramics under Irradiation with Kr15+ and Xe22+ Heavy Ions

“…In this case, the appearance of any new diffraction reflections is not observed, which indicates the absence of phase transformation processes as a result of irradiation. According to earlier studies [13,[26][27][28][29][30][31], these ceramics are characterized by a hexagonal type of the crystal structure with three main textural directions, (100), (002) and (101), the change in the positions of which characterizes the main changes associated with the crystal lattice and its parameters a and c. In this case, a change in the position of the diffraction maxima (100) and ( 101) is characteristic of the deformation of the crystal lattice parameter a, and a change in the position of the (002) maximum is characteristic of the deformation of the lattice along the c axis. A change in the intensity and shape of the diffraction line indicates a change in distortions and stresses in the crystal lattice, as well as the influence of the size factor associated with the size of crystallites.…”

“…Previously, our research group studied in detail the changes in the structural and mechanical properties of AlN ceramics exposed to irradiation of heavy Fe 7+ ions with energies up to 100 MeV [26,27]. The mechanisms of helium swelling and processes of hydrogenation of the near-surface layer exposed to high-dose irradiation (10 16 -5 × 10 17 ion/cm 2 ) have been studied [28][29][30]. Studies have been carried out to investigate the effect of the formation of impurity inclusions as a result of ion implantation in the optical and structural properties of ceramics irradiated with low-energy C 2+ ions [31].…”

The Effect of the Addition of Aluminum Nitride to the Composition of NiAl2O4 Ceramics on Hydrogenation Processes and the Increase in Resistance to Swelling and Degradation

“…One of the ways to assess the resistance of ceramics to hydrogenation processes is to simulate these processes by irradiation with protons with a high irradiation fluence (10 14 -10 15 proton/cm 2 ), which can lead to the formation of structural distortions and deformations characteristic of the accumulation of hydrogen in ceramics and the subsequent influence on the properties of materials. The hydrogenation processes themselves are accompanied by the accumulation of deformation distortions and atomic displacements, which leads to disordering of the crystalline structure of ceramics as well as a deterioration in its thermophysical and strength properties [14][15][16]. At the same time, the use of proton irradiation with specified conditions (proton energy, irradiation fluence) can make it possible to simulate hydrogenation processes at a certain depth of ceramics and to evaluate the dynamics of changes in structural and strength values, the deterioration of which will adversely affect the performance characteristics of ceramics.…”

Investigation of the applicability of post-irradiation annealing to reduce the degree of disorder in AlN ceramic to proton irradiation

“…Also, at the moment there is no direct evidence of the presence of ion tracks in AlN ceramics under ion irradiation, which also indicates a high resistance to irradiation of this type of ceramics, comparable to SiC ceramics [31]. However, there are not so many works on studying the effect of irradiation with protons, and processes of hydrogen absorption and subsequent structural changes [32][33][34][35]. In most cases, proton irradiation doses are 10 12 -10 15 ion/cm 2 , which can lead to a significant change in point defects concentration and their mobility in the structure.…”

“…In most cases, proton irradiation doses are 10 12 -10 15 ion/cm 2 , which can lead to a significant change in point defects concentration and their mobility in the structure. The high penetrating ability of protons and the high energy of protons can lead, firstly, to a change in the electron density along the trajectories of motion, which leads to a change in the density of defects, and structural changes [35]. In this case, in the case of irradiation with protons, the main role in defects creation is played by point defects, vacancies, dislocations, an increase in the density of which leads to structural disordering in ceramics.…”