Phase stability of precipitate-hardened CoCrFeNiTi high entropy alloys fabricated via laser-directed energy deposition under high-temperature irradiation

• Laser-directed energy deposition fabricated precipitate-hardened high entropy alloys . • Krypton ion irradiation of alloys was conducted at 400°C and 600 °C up to 10 dpa. • In-situ TEM recorded precipitate stability and defect evolution under irradiation. • Precipitate dissolution was mainly associated with temperature-induced annealing. This study investigated the irradiation response of precipitate-hardened CoCrFeNiTi high entropy alloys (HEAs) fabricated by laser-directed energy deposition (LDED). These HEAs were in-situ irradiated with 1 MeV krypton ions (Kr 2+ ) at 400 °C and 600 °C up to 10 displacements per atom (dpa) at the IVEM-Tandem Facility at Argonne National Laboratory. Transmission electron microscopy (TEM) characterized precipitate stability and defect evolution under irradiation. At 400 °C and 10 dpa, precipitates showed high phase stability, while irradiation at 600 °C caused intense dissolution mainly due to its annealing effect. A high density of faulted dislocation loops formed at 400 °C. The annihilation rate of dislocation loops seemed higher at 600 °C. Increasing the dose increased the number and size of voids in the face-centered cubic (FCC) matrix.