Investigation of irradiation resistance characteristics of precipitation strengthened high-entropy alloy (CoCrFeNi)95Ti1Nb1Al3 using slow positron beam

Abstract

Abstract A high-entropy alloy (HEA), (CoCrFeNi)95Ti1Nb1Al3, with a tensile strength approximately 60% higher than that of the equiatomic high-entropy alloy CoCrFeNi was developed. The increase in tensile strength results from the formation of Ni, Ti, Nb, and Al-rich precipitates, having a face-centered cubic (FCC) L12 type crystal structure, in the alloy during aging. To investigate the irradiation resistance of this alloy, it was irradiated up to 1.5×1019 ions/m2, corresponding to 1.65 displacements per atom (dpa) at the peak damage, at 300, 573, and 773\xa0K using high-energy 2.5\xa0MeV Fe ions. Applying a slow positron beam, the formation of defect clusters induced by ion irradiation and the thermal stability of defects formed at 300\xa0K were investigated. Vacancy clusters formed after irradiation with 5.0×1018 ions/m2 at 300\xa0K. Irradiation above this fluence at 300\xa0K, and at the same fluence at 573\xa0K did not significantly affect the formation of vacancy clusters. However, no vacancy clusters were formed after irradiation at 5.0×1018 ions/m2 at 773\xa0K. The high-temperatures irradiation of this HEA hinders the formation of vacancy clusters. The irradiation resistance of the (CoCrFeNi)95Ti1Nb1Al3 HEA was excellent.