中文摘要：

采用基于密度泛函理论的平面波赝势方法,研究了三轴加载的非静水压力和静水压力对铁从体心立方结构（bcc,α相）到六角密排结构（hcp,ε相）相变压力和磁性的影响,结果发现：在0—18GPa压力范围内,相对静水压力条件,随着压力的升高,bcc结构的原子磁矩在非静水压力下降低得更快;在非静水压力下,相变更容易发生,相变压力随着非静水压力程度的增加而降低;并且对非静水压力对相变压力影响的物理机理进行了讨论.

英文摘要：

We performed first-principles calculations for the pressure-induced martensitic phase transition from the ground state ferromagnetic bcc phase to a nonmagnetic hcp phase in Fe under hydrostatic and non-hydrostatic pressure based on density-functional theory,employing the pseudopotentional and plane-wave method. The calculated results show that the magnetic moment of bcc iron under non-hydrostatic conditions decreases faster than that under hydrostatic conditions as the stress increases from 0 GPa to 18 GPa. Theoretical calculations prove that non-hydrostatic conditions can significantly reduce the bcc phase to hcp phase transition pressure. The critical stress for bcc-to-hcp transformation decreases linearly as the non-hydrostatic effect increases. The physical origins of the influence of non-hydrostatic pressure on the transition pressure are discussed.