Coherent x-ray diffraction imaging of grown-in antiphase boundaries in Fe₆₅ Al₃₅

Coherent x-ray diffraction has been used to image grown-in antiphase boundaries (APB's) in a metal alloy, which represent pure phase objects. The fine structure within the (001) superstructure diffraction peak of a B2 -ordered bulk Fe₆₅ Al₃₅ sample was inverted by means of iterative algorithms that Fourier transform between reciprocal and real space, applying appropriate constraints in each domain. Since the sample object is noncompact, bigger than the beam footprint, knowing the precise beam profile was essential to define the real-space constraint. Even though a unique long-range structure could not be derived, the algorithm found phase structures that were locally unique. These were identified in all reconstruction runs by means of a cross-correlation analysis. The obtained characteristic APB morphology is confirmed by transmission electron microscopy results from the same sample, revealing nearly planar APB walls on {110} planes terminating at grown-in dislocations. © 2007 The American Physical Society.