ИСТИНА

Copper foil of 99,997% purity was used to produce a 18 microns thick and 3 mm in diameter polycrystalline disk. The sample was thermally etched under flowing H2 at 1000 deg. C for 10 h. In-plane average grain size about 30 microns was obtained. Inspection of the foil surface from both sides revealed mainly monolayer grain structure with GBs oriented perpendicular to the sample surface. Foil surface was scanned with a laser-equipped MII-4 Linnik interferometer, and its topography was reconstructed numerically. Dihedral angles were measured in the vicinity of GB grooves formed along the intersection of GBs with the foil surface. GB to surface energy ratio was calculated for about 1000 GBs neglecting copper surface anisotropy. Orientation of GB planes was determined. Dihedral angles in GBs triple junctions were measured.