  Severe lattice distortion is suggested for high entropy alloys (HEAs),
however, evidence for such effect so far is lacking, and the nature of
distortion is yet to be understood. Here, we reveal the distortion in an fcc
HEA, Al0.1CrFeCoNi, by direct imaging using electron nanodiffraction.
Information about crystal symmetry, lattice strain and atomic distortion are
data-mined and mapped from many (~10^4) diffraction patterns. Application to
the HEA reveals two embodiments of distortion, nm-sized mosaic blocks of
paracrystals and strained nano-clusters. Their interaction gives rise to
fractal strain field across nanoscopic to mesoscopic scales. As lattice
distortion impedes dislocation motion and contributes to strengthening, results
here thus provide critical insights about the complex nature of distortion in a
HEA.
