Damage accumulation in ion-irradiated Ni-based concentrated solid-solution alloys

Abstract

Irradiation-induced damage accumulation in Ni0.8Fe0.2 and Ni0.8Cr0.2 alloys are investigated using molecular dynamics (MD) simulations to assess possible enhanced radiation-resistance in these face-centered cubic (fcc), single-phase, concentrated solid-solution alloys, as compared with pure fcc Ni. The Ni0.8Cr0.2 and Ni0.8Fe0.2 alloys demonstrate higher radiation resistance compared to Ni. The total number of point defects produced in Ni0.8Cr0.2 and Ni0.8Fe0.2 is approximately 2.5 and 1.4 times lower than in Ni, respectively, due to efficient defect recombination in the chemically disordered alloys. Both interstitial and vacancy clusters are formed in all three materials. In Ni, large interstitial clusters are produced; whereas in Ni0.8Cr0.2, smaller interstitial clusters are produced but with a higher number. This indicates a higher mobility of interstitials in Ni compared to Ni0.8Cr0.2. Moreover, Ni0.8Cr0.2 shows better radiation resistance than Ni0.8Fe0.2. Larger interstitial clusters and 1.7 times higher numbers of accumulated point defects are observed in Ni0.8Fe0.2, in comparison with Ni0.8Cr0.2. Due to the low mobility of vacancies on the MD time scales, they are found primarily as single point defects and small clusters in all materials. While performance improvement is observed in the alloys, the difference in irradiation response between Ni0.8Cr0.2 and Ni0.8Fe0.2 indicates the importance of element choice to achieve the desired property.