Role of the alloying element in suppressing the negative effect of O in NiAl: Cr as an example

We investigate the effect of Cr on the mechanical properties of NiAl with O by a first-principles method. Cr is shown to replace either Ni or Al depending on the surrounding environment. Based on the calculated “local elastic constants” and empirical criteria, we demonstrate that Cr can suppress the negative effect of O, and thus improve the “local ductility” of NiAl. Here, we exemplify a useful way to estimate effects of alloying elements on the mechanical properties of intermetallics from first principles.