1. Ivan Franko National University, Department of Metal Physics, Lviv, Ukraine
2. FEM, Research Institute Precious Metals & Metals Chemistry, Schwäbisch Gmünd, Germany
3. Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory of Joining & Interface Technology, Dübendorf, Switzerland
4. Now at: ABB Research Center, Baden-Dättwil, Switzerland