Behavior of Crystalline Xe Nanoprecipitates during Coalescence

In situ high-resolution electron microscopy has been used to observe nanoprecipitates of crystalline Xe in faceted cavities in Al during coalescence induced by 1.0 MeV electron irradiation at 300 K. Atomic-level fluctuations of cavity facets result in shape changes and precipitate motion leading to coalescence. There is no apparent elastic interaction between precipitates separated by as little as 0.5 nm. After coalescence, crystalline Xe conforms by plastic deformation without melting to changes in cavity shape. Cavity volume, not surface area, is conserved during coalescence, implying that cavity pressure is not determined solely by the interface tension.