A contribution of L10 ordered crystal structure to the high radiation tolerance of γ-TiAl intermetallics

Abstract

Molecular dynamics simulations were employed to study radiation damage created in collision cascades in L10 TiAl intermetallic compound and fcc Ti-50at.%Al disordered solid solution. Either Al or Ti primary knock-on atoms (PKA) with PKA energy 5 keV⩽EPKA⩽20 keV were initiated in the two materials at temperature T ranging from 100 K to 1200 K. From 36 to 48 different cascades for each (EPKA,T) set were simulated in order to emulate an isotropic spatial and random temporal distribution of PKAs, generate representative sampling and obtain statistically reliable quantitative results. The number of Frenkel pairs, 〈NFPγ-TiAl〉 and 〈NFPTi-50Al〉, formed in L10 TiAl intermetallics and Ti-50at.%Al disordered solid solution, respectively, and averaged over collision cascades with the same (EPKA,T) was used as a quantitative measure of radiation resistance against primary damage formation. It is shown that the relationship 〈NFPγ-TiAl〉⩽〈NFPTi-50Al〉 is fulfilled under all simulation conditions, i.e. L10 ordered crystal structure of TiAl intermetallics is essential for its high radiation tolerance. However, a relatively high resistance to the formation of primary radiation defects is retained even after complete disordering of L10 TiAl that points out to the existence of additional mechanisms contributing to its radiation tolerance.