ZrNbVTiAl alloy was studied here.
Nb, V, Zr, Ta, Hf, Mo and W, commonly referred to as refractory high entropy alloy (RHEA) has been recently emphasized as promising materials for the next-generation high temperature reactors. These RHEAs exhibit better high-temperature performance due to the high melting points of constituent elements and superior radiation resistance due to their BCC-type structures which are resistant to irradiation swelling.
Nb, Zr and Al have low neutron absorption cross sections, which is necessary for an alloying element to be used in nuclear structural materials.
The atomic radius of Al (143 pm) is similar to V, Ti and Nb which satisfies one of the major criteria of formation of solid solutions in the HEA.
The induction levitation melting (ILM) was done. It is a non-radioactive technology that uses an electromagnetic field to melt and levitate electrically conductive materials. Here Lorentz force created by the field stirs the molten metal, producing a uniform temperature distribution.
In certain cases, Due to irradiation of BCC-based low-activation HEAs results in the segregation(uneven distribution of constituent elements within the alloy's microstructure). The constituent elements like Cr and V atoms migrate at the grain boundaries.
The displacement per atom was calculated to measure radiation damage in materials. The relative stability of the BCC phase was observed higher in comparison to the intermetallic phases.
In high-entropy alloys, diffusivity of constituent elements is low due to multiple sizes of atoms causing lattice distortion and slow diffusion.Thus, the effect of diffusion led growth is expected to be less prominent in high-entropy alloys, aggravating the chances of instability under irradiation.
The high yield strength (1.045 GPa) of alloy at room temperature and dynamic recrystallization during high-temperature deformation was observed.
When alloys are exposed to radiation, the intermetallic phases (secondary phases) decrease, causing the material's structure to become a single BCC phase. This is better at resisting void swelling.
Source:
https://link.springer.com/article/10.1007/s10853-024-10511-z
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