An insight into radiation resistance of D019 Ti3Al intermetallics

Abstract

A molecular dynamics study of radiation damage created in collision cascades in D019 Ti3Al intermetallic compound and a Ti-Al binary disordered solid solution with the same chemical composition is carried out. Collision cascades are initiated by either Al or Ti primary knock-on atoms (PKA) with PKA energy 5 keV ≤EPKA≤ 20 keV in the two materials at temperature T ranging from 100 K to 900 K. A series of at least 32 different cascades for each (EPKA, T) set was simulated in order to imitate an isotropic spatial and random temporal distribution of PKAs, generate representative sampling and obtain statistically reliable quantitative results. The numbers of Frenkel pairs, 〈NFPα2〉 and 〈NFPα〉, formed in D019 Ti3Al intermetallics and Ti-25at.%Al disordered solid solution, respectively, were averaged over collision cascades with the same (EPKA, T) and used to quantify the radiation resistance against primary damage formation. It is shown that the relationship 〈NFPα2〉≤〈NFPα〉 is satisfied under all simulation conditions, i.e. D019 ordered crystal structure of Ti3Al intermetallics is an important feature affecting its radiation tolerance. Nevertheless, a relatively high resistance against the formation of primary radiation defects has been retained even after complete disordering of D019 Ti3Al, which points out to the existence of additional mechanisms governing its radiation tolerance.