Atomic site occupancies and mechanical response of the eutectic C14 and A15 phases in a quinternary Nb–Mo–Cr–Al–Si alloy

Channeling effects in X-ray microanalysis have been used to deduce the character of the point defects in the C14 and A15 eutectic phases of a quinternary Nb–Mo–Cr–Al–Si alloy. It is shown that these defects are predominantly antisite transition metal atoms in the C14 phase and constitutional vacancies in the A15 phase. Nanoindentation measurements show different mechanical responses upon heat-treatment and these are related to the effects of the point defects upon the dislocations in the two phases.