中国物理B ›› 2009, Vol. 18 ›› Issue (5): 1923-1930.doi: 10.1088/1674-1056/18/5/033
刘悦林, 张颖, 洪荣杰, 吕广宏
Liu Yue-Lin(刘悦林), Zhang Ying(张颖), Hong Rong-Jie(洪荣杰), and Lu Guang-Hong(吕广宏)†
摘要: This paper employs a first-principles total-energy method to investigate the theoretical tensile strengths of bcc and fcc Fe systemically. It indicates that the theoretical tensile strengths are shown to be 12.4, 32.7, 27.5~GPa for bcc Fe, and 48.1, 34.6, 51.2~GPa for fcc Fe in the [001], [110] and [111] directions, respectively. For bcc Fe, the [001] direction is shown to be the weakest direction due to the occurrence of a phase transition from ferromagnetic bcc Fe to high spin ferromagnetic fcc Fe. For fcc Fe, the [110] direction is the weakest direction due to the formation of an instable saddle-point `bct structure' in the tensile process. Furthermore, it demonstrates that a magnetic instability will occur under a tensile strain of 14%, characterized by the transition of ferromagnetic bcc Fe to paramagnetic fcc Fe. The results provide a good reference to understand the intrinsic mechanical properties of Fe as a potential structural material in the nuclear fusion Tokamak.
中图分类号: (Magnetomechanical effects, magnetostriction)