1 Tsuchiya K, Miyoshi D, Tateyama K et al . Scr Metall Mater, 1994, 31(4): 455
2 Humbeeck Jan Van, Janssen Jan, Ngoie Mwamba et al . Scr Metall, 1984, 18: 893
3 Humbeeck Jan Van, Segers D, Delaey L . Scr Metall, 1985, 19: 477
4 WEI Zhongguo, YANG Dazhi, Wu K H . Scr Metall Mater, 1993, 29: 753
5 del Rio J, de Diego N, Hidalgo C . Scr Metall, 1987, 21: 983
6 Brandt W . In: Stewart A T, Rolling L O eds. Positron Annihilation, New York : Academic Press , 1967. 155
7 Connors D C, West R N . Phys Lett A, 1969, 30: 24
8 Bergersen B, Stott M J . Sol State Commun, 1969, 7: 1203
9 WANG Jingcheng, ZHANG Hao, SHAO Zichang et al . Scr Metall, 1990, 24: 847