1. I.M. Frantsevych Institute for Problems of Material Science, National Academy of Sciences of Ukraine3 Krzhizhanovskogo str.Kyiv 03142Ukraine
2. E.O. Paton Electric Welding Institute, Academy of Sciences of Ukraine68 Antonovich str.Kyiv 03680Ukraine
3. Institute of Physics, Polish Academy of SciencesAl. Lotnikow 32/46Warsaw 02‐668Poland