Behavior of crystalline Xe nanoprecipitates during coalescence

In situ high-resolution electron microscopy has been used to observe nanopr ecipitates of crystalline Xe in faceted cavities in Al during coalescence i nduced 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 conform s by plastic deformation without melting to changes in cavity shape. Cavity volume, not surface area, is conserved during coalescence, implying that c avity pressure is not determined solely by the interface tension.