Critical Behavior of Antiphase Boundaries inFe3Alclose to theDO3→B2Phase Transition

Abstract

By combining weak beam and conventional dark field transmission electron microscopy observations, we have determined the critical behavior of antiphase boundaries (APB) close to the second order ${\mathrm{DO}}_{3}\ensuremath{-}B2$ order-disorder transition in ${\mathrm{Fe}}_{3}\mathrm{Al}$. The weak beam technique is particularly accurate since the intensity of the APB fringes decreases exponentially when the width of the boundaries, proportional to the correlation length $\ensuremath{\xi}$, increases. The measured critical exponent $\ensuremath{\nu}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.64\ifmmode\pm\else\textpm\fi{}0.1$ is in good agreement with theory as well as with scattering experiments in the $B2$ phase.