Effect of Zr addition on the structure, nanomechanical properties, and helium irradiation behavior of the novel MoTaTiV body-centered cubic concentrated solid solution alloy

The rapidly developing technology of fusion reactors requires the development of new materials with enhanced radiation resistance. In this study, two new equimolar concentrated solid solution alloys (CSAs), MoTaTiV and MoTaTiVZr, designed for nuclear applications, were synthesized using magnetron sputtering. The MoTaTiV alloy exhibited a columnar microstructure, characteristic for materials produced via magnetron sputtering, and a body-centered cubic (BCC) structure. The addition of Zr to form the quinary MoTaTiVZr alloy led to the formation of an amorphous phase due to increased lattice distortion caused by the introduction of Zr into the crystal structure of the base alloy. To evaluate the irradiation resistance of the synthesized alloys, the materials were irradiated with 200 keV He⁺ ions. In the case of MoTaTiV, helium bubble formation was initially observed primarily at column boundaries, which serve as preferential nucleation sites. However, at a fluence of 5 × 10¹⁶ cm⁻², bubbles were also detected within the matrix. For the MoTaTiVZr alloy, due to its amorphous structure, bubbles were uniformly distributed throughout the matrix. Despite these differences in He accumulation behavior, the bubbles in the MoTaTiVZr CSA were slightly smaller, indicating that increasing lattice distortion inhibits bubble growth. Furthermore, the absence of radiation-induced hardening in both materials suggests a high intrinsic resistance to radiation damage.