Study of the Effect of Heavy Krypton Ion Irradiation on the Structural-Phase State and Mechanical Properties of High-Entropy Diborides

Abstract

Since nuclear and aerospace technology require the creation of radiation-resistant materials, studying the radiation resistance of high-entropy borides (HEBs) is relevant. They combine the advantages of single-metal diborides, such as high melting point, hardness, and chemical inertness, but exhibit superior radiation resistance. This paper provides a brief overview of the characteristics of HEBs and their synthesis methods. The effect of heavy krypton ion irradiation on the structural and phase state and mechanical properties of (TiHfZrNbTa)B2 HEB synthesized by spark plasma sintering is studied. SRIM calculations showed that at a fluence of ~1015 cm-2, the damage level reaches ~2.3 displacements per atom (dpa) at a depth of up to 12 μm.
Using SEM-EDS, the surface morphology of HEB and the binary diborides NbB2 and TiB2 was analyzed. Irradiation did not significantly alter the surface morphology, but cracks formed in TiB2.
X-ray diffraction analysis showed that the lattice parameters of all borides increased, with the largest change in the lattice parameter a for HEB (0,54%) and in the lattice parameter c for NbB2 (0,61%). This anisotropic lattice deformation likely indicates the accumulation of radiation-induced defects along one of the lattice axes.
Vickers microhardness measurements showed that irradiation causes radiation hardening in HEB and a decrease in microhardness in TiB2.
The obtained results indicate high radiation resistance of high-entropy diboride (TiHfZrNbTa)B2, which makes HEB promising materials for use in high radiation environments.