基金Projects（50501020, 50395103） supported by the National Natural Science Foundation of China Project（NCET-05-0870） supported by the New Century Excellent Person of China Project supported by the Creative Foundation of Science and Technology of Youth in Northwestern Polytechnical University, ChinaAcknowledgement The authors are grateful to Professor MITTEMEIJER and Professor S0MMER for indispensable instruction and cooperation and to Dipl.-Ing. H. NITSCHE in Max-Planck-Institute for Metals Research for support with the numerical calculations.
