Before revision: A precipitate-free zone (PFZ) refers to a localized region around the grain boundary that is free of precipitates , and (solid impurities forced outwards from the grain during crystallization).
After revision: In materials science, a precipitate-free zone (PFZ) refers to microscopic localized regions around grain boundaries that are free of precipitates (solid impurities forced outwards from the grain during crystallization).