Mechanochemical penetration of helium atoms into Pd-84.5-Si-15.5 and Ni-78-Si-8-B-14 eutectic amorphous films extended in liquid He-3 and He-4

The penetration of helium atoms into amorphous films extended to fracture i n liquid helium has been investigated. It is found that helium atoms penetr ate into the eutectic alloy films Pd-84.5-Si-15.5 in He-3 (T = 0.5 K) and N i-78-Si-8-B-14 in He-4 (T = 4.2 K). The spectra of helium liberation from t hese materials after deformation are obtained upon dynamic (4-5 K/min) anne aling at T = 293-1323 K. The maximum amount of helium is observed in the re gions of local plastic microshears running across the whole width of films and also in the sample regions containing fracture macrocracks and isolated groups of slip bands. The spectra of helium liberation from different regi ons of destroyed samples show several peaks that correlate with the tempera tures of crystallization and melting of the studied films. The data obtaine d are interpreted within the model of mechanochemical penetration of helium atoms through the dynamically excited dislocation-like defects, which are typical of the amorphous films under consideration. (C) 2000 MAIK "Nauka/In terperiodica".