Influence of irradiation temperature on properties change of AlN ceramics

The paper presents the results of studying the effect of irradiation of Fe7+ ions with an energy of 1.5 MeV/nucleon on structural properties of AlN ceramics at an irradiation temperature of 300, 500, 700 and 1000 K. The choice of ion type and irradiation conditions was made by studying the processes of defect formation as a result of particles effect with energies close to fission fragments of nuclear fuel (≤90-100 MeV) and temperatures 0.1-0.3 Tmelt, typical for annealing defects. From the data obtained by the XRD, SEM, EDX methods, it is established that an increase in irradiation temperature above 500 K leads to a reduction in distortions and deformation of the crystal lattice under irradiation. It was found that with an increase in the irradiation dose, amorphous-like grains with a high oxygen content are formed in the structure, which are characteristic for the impurity phase of Al2O3, the content of which in the ceramic structure does not exceed 5%. In this case, an increase in the irradiation temperature leads to a decrease in impurity phase concentration in the structure. It has been established that for samples irradiated at high temperatures 700-1000 K, the decrease in strength properties is less than for samples irradiated at a temperature of 300 and 500 K. Such a difference can be explained by partial annealing and annihilation of defects as a result of elevated temperatures. The decrease in thermal conductivity coefficient in irradiated samples is due to an increase in defects concentration in structure, as well as a decrease in their mobility.