Irradation-Induced Lattice Distortion Dependent on Ion Species in Refractory High-Entropy Alloys

Body-centered cubic (BCC) refractory high-entropy alloys (RHEAs) are proposed for the next generation of materials suitable for fusion reactor components due to their outstanding high-temperature strength, and radiation tolerant properties. It is widely believed that radiation tolerant properties in RHEAs originate due to inherent sluggish diffusion within the alloy, impacting vacancy and interstitial migration. While many studies report radiation tolerance in RHEAs, dynamic defect microstructural perspectives remain limited. This study investigates Mo-based alloys with varying degrees of chemical complexity to gauge the interplay of increasing solute effects under radiation. Ultimately, we probe the impact of vacancy bias on defect evolution through <i>in situ</i> experiments conducted using single- (1 MeV Kr²⁺) and dual-beam (18keV He⁺ and 1 MeV Kr²⁺) ion irradiation. The dual-beam condition is intended to impart vacancy stabilization bias, and consequently, we recognize striking impacts on global lattice distortion. Local divergence in structure produces interfaces that act as sites for dislocation annihilation, contributing to an overall reduction in dislocation size. The objective of this work is to discuss the microstructural implications of altering defect mobility in complex alloys, offering insight to dynamic lattice effects of RHEAs in radiation environments.